The best way is to open and read several of the fine examples CCS supplies in the 'examples' folder as well as reading the 'help file( press F11 when your project is open).
Read the comments by Ttelmah in these threads on how to wake-up from
sleep and read incoming RS-232 characters:
http://www.ccsinfo.com/forum/viewtopic.php?t=36125
http://www.ccsinfo.com/forum/viewt ...