Samsung Galaxy S II

Remove the back cover

Turn the back of your phone towards you.
Take hold of the top right corner of the back cover and remove it.

Choose option

Choose one of the following options:
Insert SIM, go to 2a.
Insert battery, go to 2b.

2a - Insert SIM

Place your SIM as illustrated on the SIM holder.
Slide your SIM into the SIM holder.

2b - Insert battery

Place the battery in your phone (top first), matching the battery contacts with the phone contacts, and press the battery into place.

Replace the back cover

Place the back cover on your phone (bottom first) and press the back cover until it clicks into place