How to replace the battery in a Nokia g300 cell phone

Can anyone tell me how to replace the battery in my Nokia g300 TracFone? I understand it's a pretty involved process but I have not been able to find a step-by-step or a video with English explaining how to do this. Also what battery do I need to purchase to replace the one that I have in my Nokia g300 now. It runs down rather quickly. I'm already at 65% and I've only had the phone on since 6:00 a.m. and it's 10:00 a.m. now.

Along the same line, does anyone know how to keep apps from loading on the Nokia g300? I have a number of apps that load when the phone turns on that should not be loading in the background and slowing down my phone.