Here are some tutorials for the start of a 4"x 4" mini album to fit into the box/frame.  These are the measurements...

4 1/4 "  x   4 1/4"   mountboard of chipboard for the cover
5 1/4"   x   5 1/4"   paper to cover front of mountboard
4 1/8"   x   4 1/8"    paper for back of mountboard

The pages are  4" x  4" cardstock

The folding mats for the backs of the pages made from D/S papers are 3 7/8"  x  7  6/8" and scored at 3  7/8"

Hope you'll have a go.

Will be posting more tutorials soon.