To complete level one, you go through the door, for level two, you go to the portal. Watch out for flame jets and the Minotaur! Collecting the bow will give you the ability to shoot arrows! Arrows will cripple the Minotaur. (disable him for three seconds)
I don't know what's up with the first flame jet (hurting you even when you don't touch the fire) and the music, but if you can figure it out, feel free to post a remix of this!