1) learn how to stand up straight in them. don't move until you can control yourself standing upright, unaided.
2) when you can finally stand, shift your weight slightly to your left foot.
3) assuming you don't fall in step 2, push your right foot gently to the back & right in a soft motion. (diagonally from your other foot) this should propel you slightly forward.
4) repeat step 3, but shift the weight to your right foot.
you can practice this at home in your bare feet. shift the weight to one foot and imagine pushing diagonally towards the back with the other foot to propel yourself. also practice standing on one foot at a time with the other leg extended. a lot of this comes down to balance, which requires good core strenghth. which is why it's easier for kids than it is adults.
Good luck & have fun!