How to braid cornrolls???

I think the thing you mean is cornrows, like the ones Alica Keys has? They are usually fairly small braids that are braided very tight to the scalp, they are very similar to a french 3 strand braid and not that hard, but they need practice. This site has helped me a lot: http://www.dreamweaverbraiding.com/ You can find numerous ways of braiding there, very well explained and with lots of pictures. Enjoy!