Make sure you use a stabilizer underneath the background fabric or your applique will "tunnel" and get stuck in the feed dogs. There are lots of stabilizers to choose from. If you have a JoAnn's near you, go to the notions aisle with your 40% off coupon and find Sulky stabilizers. They come on a roll or flat sheets. I like the roll because I can cut it to what I want. You might like the adhesive kind since it will keep your block nice and flat, but be careful when taking it off the back that you don't stretch your background fabric. WORST case scenario, you can use regular paper, but that will dull your sewing machine needle real quick. It also makes a funny noise when sewing through paper, don't worry about that.
Edit: Here is a link to Sulky stabilizers at JoAnn's website - and they're on sale right now for half price!
http://www.joann.com/joann/search/se...lky+stabilizer