dot c

what can i do with .c source? i mean... how to compile... and how to execute it???

In c++ it is actual code used written by the programer. Sometimes you have .h for headers, they all play a part in creating a program. Example, I might have all my headers in one file "iostream.h" and all my code in another "blah.c"
Be careful about compiling, just taking straight c source might not exactly work. Usually it's a way for coders to exchange working code to integrate into each other's programs and sometimes, it's the full blown thing. If you have never done anything with programming, I wouldn't recommend trying to compile these and run them. Sorta like don't open any attachments from strangers because you don't know what it does. Same here with source, don't go compiling and running anything if you can't read over it and get a general idea of what it's doing :D

All that is right and every thing but *.c files are c programs *.cpp are c++ programs. You could compile them or view them to see what they do or if there are holes , or you could create holes and compile them and give them to people.