Get the current edition of American Woodworker. This has an article with many pictures of the equipment that can be used to build a picture frame. Or you can just use wood filler and paint it. Your problem probably is the sliding miter gauge. Get a plastic triangle from the Stationery Department and use it with the long side on the saw blade to set your miter gauge. Bet you will find that the markings on the gauge are off by a degree or 2.