How to feed animals in minecraft?

The only animals you can tame is the rideable ones - and in most instances, you just need to dump a saddle on them (for the pig you need a carrot on a stick).

But you can use wheat to get sheep and cows to follow you (pigs may need carrots, I can't remember) - and you click on them to feed them (feed two of the same breed and they'll make a baby)