I'm in the Valley of the Kings and still don't know how much experience I have or how much I need to level up.

Do you see the bird in the attached image in far left upper corner of the screen?
Slightly to its right are these bars: red = health, green = stamina, blue = magic, now look below the magic bar.
See the 5 and the light purpule half circle around it? That's the experiance bar.

Other than that the game gives no incidation of your EXP and it's not reprisented with a numerical value either.

You're welcome. :)