Sorry for the late feedback, don't have much time at the moment. I'll try not to mention stuff that's already known or mentioned.
Nice to see, that the map doesn't leak, is lighted and that you don't want to go with anything to extravagant for your first maps. All in all, that's not the worst start.
I'll start with the entities. You have one flag for each team, so I guess you want to have a CTF map. CTF is "gamemode" "4" in the worldspawn. At the moment, you are using 2 (single flag).
I'm not sure why you're using two base entities for the 1st team. Might want to delete the double.
I wouldn't add the year to the message, to the map name and/or to the map itself. I did the same with dome, now i don't really it. But it's your choice.
Add "angle" "#" to the player spawns, that a player doesn't look in front of a wall after spawning.
There're two warnings while loading the map ingame (PB_droptofloor). These entities are one item_pballco2 entity and one item_pballammo entity in the red base. Just move these two entities out of the brush (the wall). If it's ok, the warning should disappear and you should see the entities ingame.
That's it with the entities.
In additional to the wrong barrel size, you should try not to use to many sides. You also need to change and align the bottom texture, too. At the moment you just changed the top textures.
Use 8 sides and a radius of 24 units (diameter of 48 units). After that change the top and bottom textures and lock the textures with Alt+L. Now you should be able to copy, duplicate and move the barrels around without destroying the textures. You could do the same with the boxes. Locking textures avoid lots of misalignments and can be very helpful, because it's much work to align all the stuff afterwards.
I can also add screenshots of misalignments after you fixed and aligned all stuff as best as you can. At the moment it's useless, if you've already fixed some stuff T3RR0R15T told you.
Map is online @ [OTB] Beta! Keep on working