what is the easiest way to get rolled fondant onto a rectangle/square cake??

Hi, you have to roll out the fondant and then take it to your rolling pin. Then put it on the cake. Its the easiest way to do whether its a square or a round. Here is a Wilton link for you to see, so you can understand a bit more!

http://www.wilton.com/decorating/fondant/rolled-fondant.cfm

HTH.

First, I would highly recommend Sugarshack's Fondant DVD. It's amazing.

As Sharon (Sugarshack) points out, when covering a square cake with fondant, start at two corners (not diagonal, opposing corners, but side-by-corners). Form the two corners sharply and smooth the side in between the two corners. Then, smooth another nearby corner and smooth the side in between two corners. Form the third corner and smooth the side between two finished corners. Then, form the final corner and smooth the final side. That's how I've done it.