AI got asked to make a friends wedding cake. What she wants is simple and elegant. I needed to know how to make it look like snow. I've seen some gorgeous ones and I know what she wants but how do I get the sugar to stick to the fondant? Or leave the fondant out and just cover the cake in butter cream then cover in the sugar?

Do you have a picture of the effect you are trying to achieve?  If you are going to use fondant and sparkle sugar, you could simply wet the fondant with a (very little) bit of water.  Or you could brush on some piping gel and stick the sugar to that.

Thats what i was thinking. i just didnt think the water would be a good idea for the sugar. i just uploaded a  pic of the effect i want. its the only pic i have so far...

With that large an area to cover I'd go for the piping gel, but I'd use only a very very thin layer and I'd do it in sections so you don't have to keep reapplying it to areas that have dried before you get the sugar on.

ASo should I do fondant 1st then?

If you are comfortable using buttercream, I'd go for that instead.  Otherwise you would cover the cake in fondant, brush on a minimal amount of piping gel and stick the sugar to that.  You won't achieve the same look with the fondant because the sugar will not be as thick as it will with a buttercream base to stick to.  I'd do a small test cake now in order to test the look before making a decision as to how to proceed.