I have a leak in my overflow how do I fix it

If it's in the hose replace the hose, if it's in the bottle, get a new one. Should be plenty of compatible ones in your local pull-a-parts. Just go to one of those, their computers will direct you to an equivalent one if they don't have an exact match. The radiator works on suction when it tries to draw coolant from the overflow, so having a hole in that bottle is going to impede that.

If the hole is small like pencil sized or smaller some JB weld should fix it. If it is cracked or the hole is larger then replace the reservoir. How the heck did you get a hole in the reservoir?