I'm working on some new designs on cake dummies and first time I covered a square in fondant I could tell it was too dry so I put it in microwave a few seconds and added shortening. Now it's tearing on all edges and yes I sanded all the edges (and the fondant is not warm...and it's kneaded well) . I'm using cheap Wilton fondant since it is only for a cake dummy. Any suggestions?? Also I'm using that long roller from Wilton. This thing sucks! I keep getting lines in my fondant. Haven't covered a cake in fondant in awhile and forgot how much I hate this roller. 

2 questions....help with tearing fondant and also suggestions for a good roller with handles. Thank you!!

This will probably help.  Take a look at these two videos.

http://sweetwise.com/videos/how-to-cover-a-cake-with-fondant-using-the-mat-by-sweet-wise.html

http://sweetwise.com/videos/cake-basics/fondant-survival.html

AThank you!

Get rid of the rolling pin lines by using a fondant smoother on the fondant before you pick it up to put it on the cake.  And if your fondant is tearing, you probably didn't sand down the corners of your dummy enough or rolled your fondant too thin.  Hope this helps.

AThanks!