Newbie question on Linux libraries

[GCB-Toronto]

I am running Codelite under Windows to re-build a program originally built under a WIN32 RTOS. I wish to port this program to run as a Linux application later on a Linux platform. I have been able to compile the program and had expected to see a number of linker errors referencing missing WIN23 functions. This is however not the case and for example if I try to call a typical POSIX function it is not available in header files. I am supposing that WIN32 functions are bring provided by default by GCC from libraries.

My questions are:

(1) Where are the libraries located in the typical codelite installation? Are these supported via DLLs?

(2) Is there a way to replace the existing libraries with Linux libraries?

Apologies for my ignorance on this but I am just getting my feet wet in Linux development.

Gerry