I have never filled a cake. I dont know where to start????

I need to fill a stacked cake with 2 different types. Any ideas and how do I do it?[/quote]

First you will need to mix some frosting up really stiff. (and I mean stiff!) You need it stiff so that when you are frosting the cake, the pressure from you smoothing the cake does not squish the filling out. When you put your filling in, don't fill to the top of your frosting dam, or it will squish out. I also tend to put more filling in the middle so that it squishes to the edges evenly without squeezing out.
http://www.wilton.com/cake/cakeprep/stacking.cfm here's a guideline to help you.

I would use a piping bag and a large writing or star tube (big one!) to help you get an even layer all over. If you use a spatula, you might not get the same amount over the entire surface. Until I got the hnag of it with the spatula, using the piping bag helped me a lot.

And if you do use really stiff icing, make sure your cake layers are chilled or even partially frozen or you risk ripping them if you use the spatula to apply the filling