I think I have an idea of what you're talking about. I had to do something recently myself for my "shawlpack
." I used a varition of heat'n'bond interfacing
- except in came in red packaging. Basically, it comes with two sides of adhesive - one covered in a wax paper, the other side bare adhesive. You place the adhesive side down on your fabric (this will be the fabric for the design; the paper side should be facing up) and, with your iron at medium heat, press the iron on the paper side for around two seconds until the section is nice and stuck on the fabric. Then you cut out the shape you want, peel off the paper. With adhesive side down, you place the design on your final fabric, and press it on with iron for about 8 seconds (for cotton fabrics - any other fabrics you want to keep it on for a few more seconds).
Those should be the instructions nearly word for word on it. Whatever the case, if you go to JoAnn's or a similar local chain, they should have it right next to the normal purple packaged heat'n'bond. If I can find it for you, I'll link it.
EDIT: This is the stuff
. I've never seen this site, so I wouldn't recommend buying oit from here simply because I've never heard of it. But basically, that is the type of HeatnBond you want, if I got what you're looking for right. >.> Also it's like less than $4 at JoAnn's so I definitely wouldn't recommend getting it from that site just for that reason alone.