It's been a long time since I flew in to Carlsbad, and I haven't checked my AFD, but I think they have a tower there. If so, tell Ground that you will be requesting flight following to TOA, and (if they have time) they will try to coordinate request with the TRACON (Terminal Radar Approach Control, i.e., SoCal Approach). If they can, they will issue you a discrete squawk prior to takeoff, and a departure control frequency. As you clear the immediate confines of the airport, the tower will tell you to contact departure on 1XX.X. Read back the instruction, i.e., "Cessna 77 Victor, departure on 1XX.X," then change frequencies. Listen on the new frequency for a moment, to ensure that you don't transmit over another transmission, then key the mic and say "SoCal Departure, Cessna 77 Victor (use your actual tail number) off Carlsbad, 2,000 (tell them the altitude you're passing through, as they need it to verify your mode C squawk, and it will save two more transmissions in busy airspace), VFR to Torrance." When the radar controller has identified you, he will either say "Radar Contact" or "Ident," in which case you push the Ident button on your transponder. After he observes your ident, and his data tag confirms your N number, he will say radar contact (he can only say that after he positively identifies your aircraft on his radar scope). He may give you vectors, which you must follow (that constitutes an ATC instruction), or may not, and you then continue your own navigation on your planned route.
Now, if Carlsbad is not a controlled field, you depart normally and , once clear of the pattern, contact SoCal approach on the appopriate frequency (check the AFD, and it will be on your San Diego Class B airspace chart in your area). Again, listen on the frequency until you hear an opening, and say "SoCal Approach, Cessna 77Victor off Carlsbad, request flight following to Torrance." You will get one of three possible replies: 1) "Cessna 77V, SoCal Approach, squawk 1234, say altitude," 2)"Cessna 77V (or Aircraft Calling SoCal) stand by, or, 3) "Cessna 77V, unable flight following, maintain VFR and remain clear of Class B Airspace," depending on the controller's workload at that time. In any of those cases, continue on your planned flight. If the response was No. 1, the controller will call you to say radar contact when he has identified you on his scope, and may or may not issue instructions. Under No. 2, he will call you back when he is able, at which time you can give him your new position and make your request. Under No. 3, of course, continue on your planned flight. I do recommend listening to the frequency, whether or not you are receiving flight following, as it will help you in looking for traffic.
OK, assuming you are receiving flight following, as you fly from Carlsbad towards Torrance, it is likely that you will be handed off from one controller to another at least once or twice, as you pass through various ATC sectors. When this happens, the controller will say "Cessna 77V, contact SoCal Approach on 1XX.XX. Read back the new frequency, listen for a moment before changing (your controller will correct you if you got it wrong), then change frequencies, listen for an opening, and say :SoCal Approach, Cessna 77V, 6,500 (or whatever altitude you are cruising at). You will get a reply, such as "Cessna 77V, Socal, Roger." Again, the altitude report to your new controller on initial contact is necessary for him to verify your Mode C readout on his scope. Along the way, your controllers will call out other traffic which may be a possible conflict, such as "Cessna 77V, opposite direction traffic, 12 o'clock, 7,000." This will help you in visually locating other traffic. Respond with "77Victor, looking." When you spot the traffic, report "Socal, 77 Victor, traffic in sight." This will let the controller know you will maintain visual separation from that traffic, and he can continue the rest of his work. IMPORTANT - the controllers cannot call out all traffic to you. Their primary duty is separation of IFR aircraft, secondary duty is separation of IFR aircraft and other participating aircraft (you fall into the participating aircraft area here), and their last priority is VFR flight following, including calling out traffic. You are in very busy airspace, in which there is a LOT of IFR traffic (even on clear days), so you need to rely on your own Mark I Eyeballs to watch for traffic - don't go to sleep when the controller says "Radar Contact," 'cause he (or she) won't be able to alert you to every possible conflict.
OK, now that I have your attention again :), when you're nearing your destination, but still well out, tell the controller that you will be off frequency for a short time to check ATIS at TOA. Switch over, copy the ATIS, then switch back to your Approach Control Frequency that you were on, and let him know you're back, with Information Alpha (or whatever the current ATIS designator at TOA is). Don't forget to reset your altimeter to that advertised on the ATIS. When nearing the field, advise the controller that you are going to begin your descent. You're not on an IFR clearance, so you don't legally need to do this, but it will help the controller do his job of separating participating aircraft from IFR aircraft, and he'll probably tell you if you are about to descend into the path of a 747 coming up behind and below you inbound to LAX. As you get closer to the airport, you will be told to "contact Torrance Tower on 118.1 (or whatever the correct frequency is, I don't remember offhand). Roger the transmission, repeating "tower on 118.1," then change frequencies. Listen for an opening, and say "Torrance Tower, Cessna 9977 Victor, seven southeast (or whatever your position relative to the airport), landing with Alpha (or whatever else is the current ATIS designator). The tower will then issue you instructions and sequence you into the pattern for landing.
There, that wasn't so hard, was it? Flight following is a good service, and most controllers will go out of their way to give you as many traffic calls as they can, but they can get really busy with IFR traffic, which is their real business. They will be watching over you. By the way, it is a good idea on your initial contact, or immediately thereafter, to let them know you are a student pilot - they tend to take extra good care of you, then, as they know you're still a bit of a fledgling winging his way through some of the busiest airspace on earth. That can't hurt on your initial call to Torrance Tower, either (for instance, slide in that "student pilot" just before "landing with Alpha," just in case the approach controller didn't tell the local (tower) controller during his landline coordination, or if he just gave you "radar service terminated, squawk VFR" before you got to the airport, in which case he probably didn't let them know you're coming.
One other hint: if you don't have one, pick up an AFD (Airport and Facilities Directory) for your area at your local pilot shop or FBO. In the back of that book, there are TEC routes (Tower Enroute Control) for IFR flight throughout southern California. While you won't be flying IFR, you may want to look at those routings between Carlsbad and TOA in your flight planning, as that might enhance your chances for getting flight following. Discuss it with your instructor, of course.
Have fun, you're going to enjoy the flight!