My recommendation for a beginner would be to buy a backpack you like and sew the webbing on. Get a bunch of nylon webbing and sew a bunch of bar tacks to create

My recommendation for a beginner would be to buy a backpack you like and sew the webbing on. Get a bunch of nylon webbing and sew a bunch of bar tacks to create attachment points. Edit: I've done this by hand sewing hard points onto a canvas bag. Ymmv with a machine or other material