These Flat Backs are called "hot fix" meaning there is glue on the back of them. You use a hot fix tool. It's a wand that you plug in and it gets extremely hot and you put it onto of each bead and hold it there for like 3 seconds and it melts the glue and it sticks to whatever when it dries. I wouldn't recommend using an iron just for the simple fact that the beads will move when you place the iron. If you don't have the wand of your careful you could use the point on the iron to heat each head though.
Are these iron on? In the pictures they show it with a iron on the package? Can you take a pic of the back of the package if there's directions etc on the back? Thanks!