It is sometimes hard to visualize even weirder to explain.
The interfacing is on top with the glue up. The fabric is placed with the right side up and the wrong side down. Sew along the pencil line, this creates the applique shape. Trim around the applique piece. Cut a slit in the interfacing and turn the applique.When turned the glue is against the wrong side of the fabric. Iron the applique flat, being careful to turn the edge under so the interfacing doesn't show. I then use a glue stick to stick the applique to the back piece. I don't remember whose method this is, I'm sure it was on youtube somewhere.
When I started this method, I used the glue on the interfacing to press the applique on the back. It didn't work as well for me, the applique was puffier and hard to place correctly.