This guide shows how to replace the battery in the LG Chocolate Touch VX-8575. No background information is necessary.
Using your thumb, apply pressure to the back cover while sliding it down and off.
Lift and remove the back cover.
Locate the battery. It is the large black rectangle with the LG logo, a model number, and battery information.
Using your thumb or thumbnail, insert a thumb into the crescent indent just below the battery and apply pressure to the battery, pushing up and away from the phone. It will come out easily.