Actually, your feet should not touch the ground while seated on the saddle. This is a big mistake 'newbies' make. If you need to stop at a light, you lean the bike to one side, disengage one cleat, get off the saddle, and touch the ground with one foot.

Saddle height should be set to have just a slight bend in the knee at the bottom of the pedal stroke. The shop that sold you the bike should help you get this set up correctly. Saddle fore aft too needs to be set, as does cleat position, for optimal performance and comfort both.