Wearing safety gear also makes you feel more confident. To do a wheelie, you will first need a motorcycle. Any kind of motorcycle will do. I personally have a friend that wheelies his Gold Wing. For our purposes I will assume you ride a bike with some sporty capability, though the process is the same for all bikes.
Dirt bikes are good to learn wheelies on, because they crash cheaply.
Friends' bikes are similar in this regard. If your motorcycle does not answer, don't worry, motorcycles don't usually answer anyway. Practice wheelies somewhere you can be an idiot on a motorcycle without many people minding. Alternatively, in front of girls' schools and in front of hospitals are good places to practice wheelieing. The Man Hates Wheelies Cops HATE wheelies.