Okay, you say zero snowman making experience. Everyone's giving idea on what it should look like and none on how to do it. So hopefully this will help get you started.
~The base needs to be bigger or it will fall over.
~Arms don't work very well. The snow is too heavy to support its own weight. That's why you see pics of snowmen with stick arms.
~Start by making a snowball, put it on the ground and roll it around. It will get larger as you go. If you only have a few inches of snow plan on starting a distance away from where you want it to end up. Zigzag back and forth in lines close to where you just rolled to get the most snow. If you push the balls randomly in the area you'll end up using up all the snow close to where you have the base. Or at least you'll end up pushing the balls a lot farther because you'll spend a lot of time traveling over tracks from previous rolls.
~Pack snow into the cracks between the balls to help steady each one.
~Don't get too carried away with winning. This may be a once in a lifetime thing. Have fun with it. Its the memories that are the winners!
~Let your 5 year old do the decorating. Let his creativity shine.
I'll be watching for the pics! Have fun!