If you don't have a light box and want one that can be used anywhere, no plug required, weights practically nothing, sits on your lap and is cheap get one of these:
http://www.crayola.com/products/ligh...g-pad-product/
I bought one today at Walmart for $20.
It works great. it holds a 8 x 11 1/2 paper but any size could be used. I put a printed pattern on it and could see through solid bright yellow fabric perfectly. I did tape the pattern to the pad using painters tape so it wouldn't move at all. If I was a die hard appliquer I'd have a pro one, but this one does a fantastic job for me.