Just bought a new extended battery how do i set it up so my phone notice the change
I'm no expert, not in the least, but I believe that since the battery is an external unit of the phones working, you wouldn't have to do anything for it to do its magic.
Like a car using gasoline, the car is going to continue to operate until the gasoline runs out. The more gas you put in, (ie. the bigger battery), the longer the car will operate successfully.
Best of luck with your battery, I just order two the other day for myself and a friend and can't wait to test it out!
After installing your new battery boot into recovery. Then wipe battery stats. Charge it to %100, then let it die. Charge it fully again and you're good to go. I noticed no improvement with an extended battery until I did this.