How to make an icon?

There are some free online photo-editing websites you can use, if you're just starting I would recommend picmonkey.com as it's the easiest to use. Pixlr (online) and Gimp (free download) are pretty good but they're more confusing so it's best to wait until you're more confident with making icons before you start using those.

Disneyscreencaps.com is the best place to get screencaps from, they have a huge range of Disney and other animated movies on there.

Good luck! And don't forget most icons for contests should be 200x200 max size - picmonkey.com has a resize option that will do that for you.