There is an inexpensive craft booklet named _Do It Yourself
Framing: Creative Matting Made Easy_ by Kaye Evans.  It is #
8300 from Plaid Enterprises, and available at many crafts
stores.  If unable to locate it, you might want to contact Plaid
directly:
              Plaid Enterprises, Inc.
              P. O. Box 7600
              Norcross, GA 30091-7600

There is also a video showing how to finish many types of
projects, which includes framing.  It is advertised in "Crafts"
magazine, and available from:
              PJS Publications, Inc.
              Box 1790
              Peoria, IL, 61656
              1 (309) 682-6626