What do i do if i Swallow a small piece of glass?

Once the glass is swallowed there is really nothing you can do other than to allow it to pass through your alimentary canal and be eliminated in a bowel movement. You might benefit by eating a large meal, both to help move the digestive process along, and to possibly provide some cushioning for the glass. You may wind up with some internal cuts or scratches, but they will probably heal. If things go badly, you might need an antibiotic treatment. But wait and see.