I want to start a club in my college to help kids with cancer in africa. How?

Admirable. Great cause, one disease need urgent help in africa, many charitable organisations seeking help (funds) is burkitt's lymphoma, effecting children in equatorial africa. They desperately need medications, look for a 'not for profit organisations' like blfundafrica. Org, it is admirable in your young age to involve great projects like this. Good luck.
Look around. There may be no specific way, but, talking to people at the nearest cancer center is a great start. Some places might even have a program for this. The peace corps, and other similar organizations may also help.