New Aftermarket Ecm Replacement?

After being told by a mechanic that the ecm in my 93 civic was bad and being told that it would cost me $750 from a dealer, i chose to find one myself.
I replaced the ecm with an aftermarket ecm from Python Injection, and it had no effect. I was wondering if ecm's need to be programmed with some fancy diagnostic machine or something when new aftermarket ones are put in, or if they should just work automatically.
any help would be greatly appreciated.