I suggest you take this and a few more photos to your local hardware store to ask for help.

That looks like a serious crack.

ty i will

You need a tub overflow gasket. They are beveled/slanted/canted to fit the angle of the tub mated to the overflow pipe. Measure for the inside diameter of the gasket. You should be able to push the overflow pipe back a bit to understand how it slips in there. The coverplate notch goes on the bottom, and the water should never be filled to reach that point.

I'm sorry, but is that black line a crack in the bathtub?

3onthetree, that where I patched the tub I need to cut that string, thank you so much for the information, do the gasket fit inside the cover of the overflow cover or in the actual hole??

blubird , that's just where I had to patch the tub so I need to cut the string.

The gasket goes inside the tub hole on the back face between the tub and the overflow pipe. The coverplate screws into the overflow pipe pulling it up against the tub, which compresses the gasket.