I am going to assume you are repairing copper pipe. It would help if you found a handy friend to give you a hands-on demo. If you don't have one of those handy people handy, you can ask a hardware person to show you. It may also help to buy a book. I will do my best, but I don't plan to write a book.
You need to purchase a few supplies first. You may be able to purchase a kit, but individually you need a propane torch, propane canister or MAPP gas, a pipe cutter, lead-free plumbing solder, flux paste and either emery paper or pipe cleaner wire brushes and pipe and fittings. Your first leak is expensive and the rest is fairly easy.
Determine if your pipe is 1/2 or 3/4 inch diameter and locate your leak. You need to know in order to buy the right fittings. If the leak is on a straight section, you will need to cut out the leaking piece and use straight connectors to re-assemble. If the problem is a fitting, purchase the appropriate El or Tee or whatever.
For all repairs you must shut off water to the pipe section and empty the pipe of water. The pipe will empty in a big hurry if you cut it so we will assume that is what you will do. Cut out the bad section or fitting. Then select fittings and pipe sections to repair. All fittings and pipe to be soldered must be cleaned bright with the emery cloth, then fluxed. Apply heat to the fitting and touch the pipe near the fitting with the solder wire, it will flow into the joint. Make sure it flows all around, then use a damp towel to wipe off drips of melted solder (optional). Repeat until done.
Any questions? Can you handle it? Post back and good luck Carla.