The big knob in the upper left looks to be stitch width, for zigzagging. The control right below that, labeled 1 2 3 4 0 I think might be for making button holes, leaving it at 0 for regular sewing. The big knob to the right of that should be stitch length which would change the numbers on the gauge right above it. It also appears that below the Reverse button you have a Left Center Right switch to change the needle position.