just make it fun and noisy, the kids will just want to play. A few basic skills to work on in games.. pass, tag and running into space. Pick a couple of games each week that help them pick the basics  up... a passing one and a tagging one. Nothing complex, kneel down & give only a couple of instructions and off they go, build in extra bits as they go, they often have good ideas too for added rules. Positive feedback.  Oh and make sure you keep them warm when the weather turns, sounds basic but really important at this age. I found you just want to keep them engaged and wanting to come back, u6 is a combination of fun and crowd control :) good luck