adding functions in easyC

Hi,
I downloaded the 2007kickoff demo.
While this project is on, I explore in my easyC library and likes a certain file. Can I add this function for my kickoffdemo code, so I’ll have one more function for my use?

If so, when I open a library, or open a zip file that someone here at the forum recommaneded and attached, is there a way to add all of them at once, on order for me to have as many possibilities for programming as can be be?

Thanks.