I'll say beforehand the following isn't personal.
You need to remake this map, completely. Layout up.
To start, the layout is small, the yard is pretty unoriginal, and everything is cramped. Your ramps (should be stairs) need to be a 2:3 ratio, so for every 12 units over, a stair goes 8 units up. Your map is also fullbright, so you need to add lights to the map. Additionally, use the skybox texture to use an actual skybox. If you want to make a custom skybox search the forums for such a tutorial. As far as lighting goes, look up "sky list" on developer.valvesoftware.com, at least for your light_env that is. Add normal light entities to make the map light. Also, a word of warning, 2fort remakes, or maps of similar design don't go down too well here, as we (or I at least) view them as pretty unoriginal.