How to make a .h file?

I have some code I'd like to use by having an include statement using Borland C++. It is just C code not C++.

How do I do this?
Can you just copy the .c file to a .h extension?
Are there any Environment Variables I need to set to find the .h file or it there a specific directory it should be in to work?

Thanks in advance for any help!!!!!

 

It should, make sure to still specify #include files that you need at the top too, ie. sys/types.h or whatever you need, make sure you don't have name collisions with other functions (or main() ), You may also want to add function prototypes at the top of the file to make sure you're functions are not accidentaly being passed the wrong arguments.