Drove with emergency brake on down freeway and now when i'm backing up it squills and is resisting alittle?

My break light wasn't on so I forgot to release my break. I drove down the freeway doing 70-80 mph for a bit. I have a 2000 ford explorer. What did I screw up? And can I fix it myself?

Replace your rear brakes, if you know how

Also check your drums for cracks caused by overheating if no cracks still have them cut