Well, sorry, I will try to be more clear this time.
I'm trying to learn how to use arduino to communicate with software. I know some C and PHP. I would like to be able to build a email checker, that would, for example, use PHP to get the information from the EMAIL, and if there is a new email, get a program in C that would send some serial information to arduino to turn a led on. I found something like that on the web, but using python, and I couldn't get how it works. If anyone could give me some advices, it would be nice.
Another thing would be to send some information from arduino to a program in C, for example, the number of an variable of somethings.