[terry1156]

You need to keep track of the amount you purchased the stock for so that when you sell, you know what the profit was. The brokerage will have this information, but it is a lot easier if you keep it someplace handy.

The amount you pay on the gains will depend how long you keep the stock. I believe there are two rates - long and short term. If you don't keep the stock a certain amount of time, it gets taxed on short term rates which is much higher than the long term rates.

This is all if you buy individual stocks yourself. If you buy a index fund, then all the information will come to you in a monthly and year end statement.