For a private certificate, you must be at least 17; however you may solo at 16. This is for powered aircraft. I'm pretty certain the in a glider, both ages drop by 1 year. Since I know nothing about gliders and logging of time in same, I'll not comment further on them. You will need either 35 or 40 hours depending on whether you attend a 61 school or 141 school. Not to worry, the national average is closer to 55-70 hours, and the cost will be somewhere between $7,000 and $12,000.
An instrument rating requires, I believe 125 hours of total time, and 40 hours of instrument time. This is realistic, so figure another $9,000 for this rating. On the other hand, if applied properly, all of the time will count towards your Commercial Pilot Certificate. Minimum age 18, total time required is 250 hours. This adds another $15,000.
ATP requires 1500 hours, but most of them will have been paid for by people paying you to fly once you have a Commercial. So the cost of the final training and checkride is probably less than $2000.
If your are really serious, check out ATP (a nationwide flight school), check out the various colleges that provide aviation ratings, and you can attend a local flight school. I prefer ATP, but all have advantages and disadvantages depending on your unique circumstances.
For all the information that you need about requirements, see faa.gov, and read FAR Part 61.