My mother in law has asked me to do a stack caked. Do I place the cakes directly on each other or do I use something in between them? HELP!!!

You need to use a board in between them...and it should be waxed or covered in wax so it won't soak up any moisture, etc. from the cake/icing.

Also, you need to put a central dowel down the center. Sharpen it to a point and be careful tapping it down.

How many cakes will be stacked?

here's the tutorial

http://www.cakecentral.com/article23-Teired-Stacked-Cake-Construction.html

Thank you all so much. I have only done a hand full of cakes and she wants this for her parents anniversary party!!! Wish me luck!!!! I think she just wants two square tiers.

I forgot to add that if you don't have dowels for support, you can use straws, like the ones you get from McDonald's. Use them the same way as if they were dowels. I cover the bottom of my cake boards with contact paper. Some people have also suggested sprinkling powdered sugar in between layers so the icing won't stick to the cake board above it.