Hm...maybe you shouldn't post your first map here, but I will write down a few things you have to learn
First of delete the box around your map, add a sky brush and fix the leak correctly. That's really important.
Then try to avoid all of this overlapping brushes (p.a. because of the little bit more complex structures like the tunnel; easy tunnels with better brushwork will be much better for new mappers) and the small dark holes and edges (most of the time brushes aren't wide enough or too wide). For beginners it could be very helpful to use a higher grid (16 is very good, for smaller stuff 8 ).
And maybe start with more easy stuff. Flames are to difficult for new mappers
But a big +1 for aligned barrels. That's very nice to see. The spawnpoints are also very good.
For the sky you should add the keys
sky ### and
_sun_ambient ### to the worldspawn. And as I said, you have to add the sky brush.
More feedback will follow after you have fixed the leak correctly. We will also upload the map then to our [OTB] Beta server.
