First off all, there is a simple way to include all project files into a single ZIP file to upload to the forum...
(right-click on the executable name in the right-hand project pane and select "ZIP project files")
That said, as czerny already mentioned, the .c file is incomplete, as a matter of fact, pretty much all the code in it is irrelevant as it is within the huge #ifdef Linux section....
In general, as Pelle's C is a Windows only compiler, you need to look for Windows specific API's to access any serial port, as you do not have direct hardware access to any of the required ports...
Ralf