Fix your leak for one thing, that would make the map at least playable. XD
In my opinion, you're learning pretty quickly, at least you know how to use different textures and it looks like you know how to line things up.
*cough*nick123*cough*.
But still, try not to post your first few maps. Practice more until you master the basics.
For your next step, you should start making a bit more complicated shapes instead of only boxes in your map. Try making barrels, that should also help you practice aligning your textures.