My two front teeth are over-lapping. What can be done to fix this?

Orthodontics. Start with your dentist to determine the health of all of your teeth, and then seek the advice of an orthodontist who specializes in the correction of malocclusions.
See an Orthodontist. I suggest you start by seeing an orthodontist to see if your teeth can be straightened. An orthodontist can tell you if that would be the best option in your case, what would need to be done, how long it would take and how much it would cost. Alternately, if you already have a general dentist, you could run that question by him or her. You need a personal exam and evaluation to start.
Maybe orthodontics. If the overlap is minor, invisalign, a removable appliance or braces can be done to straighten. If the overlap is more severe, braces with some enamel trimming is a solution. Occasionally, teeth can be veneered with porcelain to mask or correct tooth rotations so that more time consuming orthodontic procedures don't have to be done.
Orthodontics. Braces can address this. I would visit an orthodontist for a free consult.