c code for sending message through a gsm module interfaced with atmega 16

I had connected the sim 300 based gsm modem to the atmega 16a microcontroller using Rx,Tx and GND pins................. Now i want to send the data received by gsm modem from microcontroller to a pc using internet and wireless communication...........How can i do that?????????? Please give me the required procedure and the commands stepwise...........Please help.......

I had studied about UART, AT-commands,sending SMS ,making calls..........But nowhere i am getting the clear picture. I have no problem in connecting and using the GSM modem with a pc.......... But when it comes on writing programs for GSM modem use with microcontroller.......... I don't know in which IDE i have to write the program.........Either on winavr or on hyperterminal..........and what should be the programming language..........only in AT commands or some other............Please suggest some tutorials for that........................ Please help.............

check this url
https://extremeelectronics.co.in/avr-tutorials/sending-an-receiving-sms-using-sim300-gsm-module/