How do I describe a global variable

[akira32]

How do I describe a global variable(called sdl) in "please select SDL's location" when I create a SDL project?
Could somebody tell me the variable "sdl" in Code::Blocks's syntax?
Similarly to be $(~sdl) <=== error in my memory

[stahta01]

http://wiki.codeblocks.org/index.php?title=Global_compiler_variables