I want to add an image to my window as a logo. How could I do that? Is there any func or sth to do it or do i have to write my code?
Adding a textured quad to the window is a trivial thing for OpenGL to accomplish; so either you are not describing your situation in enough detail, or you really need to learn OpenGl basics and look at some tutorials.
A real simple way is to use glRasterPos and glDrawPixels.