Hi pawan,
that recieve program is written with interrupt,so when data is recieved the data will automatically store in buffer.i.e., info[check]; info[check++]=SBUF; so when data is 69 means you have completed recieved data. so you can go for check $GGA,$GGL and other. to know connect ypur GPS receiver to hyperterminal and view what all you get.
for more information you can view NMEA protocol datasheet to know the data format from GPS