I want to execeute more than 2 function in C++ at same time , how could i do this process . I think it has been done by threading , But i want to know about threading .
So if you're compiler is C++11 compliant, then go for that.
If yours isn't, then boost::thread can be used instead. This is more or less the new, standard one, except in a different namespace (there are differences, but these shouldn't matter for basic usage). So what you learn about boost::thread will mostly apply to std::thread, when compilers catch up with the standard.