This is the first song you need to learn. All banjo players know this because it's usually the first song they learned too. There are many nice variations you can play with Cripple Creek all up and down the neck.
Print out this Cripple Creek tab and listen to the song
Measures 1 and 2
Measures 3 and 4
Measures 5 and 6
Measure 7 and 8 (These are the same as 3 and 4)