[kyungjin]

Err... To do this go to File -> New...

And then select the project that you want. From there on the bottom there's a textbox where you type your file name WITH the extension. For example... If you want a C++ source file named test... then type in test.cpp. If you want a header file... for example, testlib... then type in testlib.h.

It should automatically create a file in the project that you selected.