Right now all you know is that you have a blown fuse, so replace it and see if it happens again.
If it does, then you need to track down the short.
One easy way I like is to disconnect things, put a test light on the downstream side of the fuse and start hooking things back up and see what blows it.
The test light helps to know what caused it right away because you can see the light from most places around the car.
Use the alligator clip at the fuse box and the point of the tester up where you can see it when it goes off.
On my Dart the flasher unit is almost dead center on the dash right on the top side of the lower edge of the dash.
If it's missing you should find a plug that looks like it would match this picture.
You might consider getting an electronic flasher since they don't slow down with the engine idling.
If you plug the rear lights back in and it blows the fuse pull all those rear bulbs and check the sockets.
They can get busted up inside, or the spring under the contact pad in the socket can rust or break and short to ground.
If you don't have a problem there it could be in the signal switch in the column.
