In addition to what I listed before on the dials- to either side of the long finger knob for stitch width are two silver like buttons these most likely are to lock the stitch width in place once you set it. If you don't set it you should be able to play with the width while sewing creating your own designs.
In the center of the top button the white push button is reverse. This machine may or may not require the machine to be in motions to activate reverse.
Have fun