Gsm module sim900A pin configuration

[ajperz]

Hello there... I bought a new gsm module for my project but I guess I have the wrong model chosen.. If someone can pls explain the pins that I willl use and where they are designated to..
Here the pic of the sim900A I will be using..

[ajperz]

Here's the pins label at the back .. pls I really need a help on this one.. I tried connecting vcc to 5v(arduino supply) and gnd to arduino ground. But the module cant register my sim card. I called the sim several times but still cannot be reached. Pls guys I really need a help here :((