OpenGl Suggestions! How can i achieve this:

[rawr666]

So, I am a beginner C++ programmer and i am creating a game . I want to achieve that when a character press space, it will direct him to level 1. But how do i do that. When you run it, first it will show a titlescreen() and how do i replace that scene to another scene(lvl1) when the player presses space? I really have no idea how since i just programmed a while. Thank you very much!