Here is a video that shows how to make an iron-on patch. http://www.emblibrary.com/EL/elprojects/SimpleProduct_ELP.aspx?CS_ProductID=PR1276&CS_Category=&CS_Catalog=Elprojects
You can omit the iron-on product and cover the back of the patch with an iron-on product such as Sulky's Tender Touch. You can also use fusible tricot interfacing from the fabric department.