Remove the battery from the phone.
Remove any remaining adhesive from the phone, and clean the glued areas with isopropyl alcohol and a lint-free cloth.
Secure the new battery with pre-cut adhesive or double-sided adhesive tape. In order to position it correctly, apply the new adhesive into the phone, not directly onto the battery. The adhesive should go around the perimeter of the battery compartment, but not in the rectangular cutout in the center (which is actually the back side of the display).
Press the battery firmly into place for 5-10 seconds.