Super Super easy!! I actually just took the instructions right off the back of "Ultra bond Heatbond"!
First you Draw/Print your design on a piece of paper..
Then trace it onto the paper side of Heatbond.. (trace it backwards!!!)
Next pick out your fabric and place it on the WRONG side..
Next Iron it down
Then Cut it out!!
Then peel of white paper.. place it on clothing or whatever
All Done!! (You could then sew a border to make it more secure if you like!)