Samsung Galaxy S Plus

Remove the back cover

Turn the back of your phone towards you.
Take hold of the bottom of the back cover and remove it.

Remove the battery

Take hold of the bottom of the battery and remove it.

Insert the battery

Wait for 10-15 seconds.
Place the battery in your phone (right side first), matching the battery contacts with the contacts in your phone, and press the battery into place.

Replace the back cover

Place the back cover on your phone, bottom first, and press it into place.