How to communicate to DWEET using GSM SIM900a

Hello everyone.
I have to send over some sensor values to dweet.io for cloud based storing. I am using the GSM SIM 900a modem to establish a GPRS connection and send the values to Dweet. However, I am confused how to do this. I can use the AT commands to establish a GPRS connection but I am stuck at transmitting the values to the server. How do I do this using the AT commands?