[Dev-C++] New User - question on linking files within a project

[Y&S G. <yg...@sy...>]

I am a new user to the Dec-C++ IDE, with a reasonably good knowledge of =
the
C language, but very poor knowledge of other tools (linker, debugger, =
etc...)

My problem is as follows:
   - I have been developing a program in C, with all the source code =
(main and=20
     functions) in one source file, i.e. my project consisted of only =
one file (extension .c)

   - as the program grew bigger and bigger, I decided to move the =
functions into
     their separate source files, for ease of editing;I added their =
source files (*.c)
     to the project list

   - by doing so, I am getting many compiler and linker errors (note: =
some
     of the function arguments are structures; other functions access =
files,=20
     i.e. use fopen, fprintf, ... Again, everything works fine with a =
single source
     files, containing main() and all functions)=20

I must be missing something fundamental in the structure (due to my lack =
of
understanding of how files are linked). Are there any online information =
(more
tutorial-like) on such topics?

Any help will be much appreciated.=20

Regards,=20

YG