Just switched out Skid Control ECU Help

So recently i went to autozone and used their scanner and I got the some abs codes. I did some research and I found out the problem could be the abs actuator or the skid control ecu. I spent all today figuring out how to take the skid ecu out and finally switched it. When I turned the car on all the brake abs lights were on like they were the same as they were before and my gas meter went from 5 to 1 bar. I replaced my skid ecu because when I bought this car when I was driving the car switched to neutral and wouldn't switch back until I restarted it then the same thing happened again (I should note that when my car had problems before it went from a full tank to half). I know some people talk about tech stream and how your supposed to reprogram the ecu or something can someone explain what that does and if I need to do that. . Im hoping I don't have to replace the abs actuator and this solves my problem . Thank you
I have a 2008 prius