Using the straight edge and craft knife, cut a rectangle 3 3/4 inches by 5 3/4 inches from the middle of the mat that will frame your photo. Cut from the front side of the mat to make a cleaner cut. This will be called mat 1.
Using the straight edge and craft knife, cut a rectangle 4 inches by 6 inches from the middle of the mat that will frame the mat in step 1. This will be called mat 2.
Using the straight edge and craft knife, cut a rectangle 4 1/4 inches by 6 1/4 inches for the top mat. This will be called mat 3.
Glue mat 2 onto mat 1 leaving a 1/4-inch overlap on mat 1.
Glue mat 3 onto mat 2 leaving a 1/4-inch overlap on mat 2.
Glue or tape the three-layer mat onto your photo.
Place the finished product onto the original back of the photo frame. Place the mat and photo into your photo frame.