try Shirley E. Held, Weaving , A handbook for Fiber Craftsmen, Holt Rinehart
and Winston, Inc. 1972...
an oldie but goodie.
The harness loom is simply a method for ordering the yarns into an even
'shed'. the techniques for setting up a multiple harness loom are the same as
a two harness loom. The important thing is to alternate the threading of the
harnesses.
Try finding the magazine called FiberArts. It will give you lots of ideas
about what to create, besides plain cloth.