Can your top teeth suppose to slightly over your bottom teeth?

Yes.: Normally the upper teeth are in front of the lower teeth by about one millimeter and overlap by 1.5-2 mm in a class 1 occlusal scheme. This allows for normal wear and function. When the lower teeth are in front of the upper teeth this is commonly called an under bite and should be looked at by your dentist or orthodontist.

Everywhere: In addition to the vertical and horizontal overbites described so well by dr sakurel, on the sides your upper teeth should be 1/2 tooth wider than your lower teeth. If you have concern about how your teeth fit/function, see your dentist for evaluation. Perhaps consultation with an orthodontist is in order.