All you need is:
I got mine at Hobby Lobby while they were 50% off. Only $5
2. Glue gun and glue
3. Mod Podge
5. Sheet of metal
Go to Lowe's, some will even cut it for you!
Measure and cut your metal to the size of your frame
Mod Podge your favorite paper to the metal
Hot glue your metal to the back of the frame. Its best to put something heavy on it and let it sit for a few hours.