sending mms using gsm sim900a

Hello everyone..
I am working on a project where I am using Arduino uno, Simcom sim900a gsm/gprs modem, a camera module, and a sd card module.
So for now I want my camera to take a picture for me, store it in sd card, and then send it as a mms to a mobile phone.
So far I have accomplished taking a picture and storing it in sd card module..
Now I don't know how to send a mms.
I searched a lot on the Internet, but have no solution for my problem..
Please help me.