Welcome aboard
Everyone's a noob at some point, but not for long, so don't worry about asking stuff, there's no dumb questions. So ask away.
If you're doing CQB, obviously light and maneuverable is the thing. So gun-wise, small is good: UZI, Mac 10/11, MP5K, P90, AKS74U, Skorpion, short M4, tactical shotgun etc. Keep in mind that some CQB sites are semi-auto only, and those that aren't may still have a semi-auto only rule at short ranges, so avoid anything that can't go semi-auto, such as the ASG STEN gun (well, not without modification anyway), which would otherwise be a good CQB choice. Also be aware that many small SMGs such as the UZI and the Skorpion have high rates of fire and comparatively small mags, which can easily leave you out of ammo at an awkward moment, whereas most things like an AEG MP5K or AEG AKS74U, will come with a high cap mag (typically something like 300 rounds), so there's less expense initially in not needing to buy spare mags straight away, and the likelihood is that the one high cap mag will last the entire fight without the need to reload.
Most people and most guides will tell new players to not worry about a pistol until later, and whilst that is generally good advice, in CQB, a pistol is a good thing to have to hand, and you could even go pistol only at some small CQB sites. But, it being winter, gas blowback pistols can be iffy choices, since they can struggle to work well in cold temperatures, so if you are considering a pistol, then either a non-blowback gas one is a better choice, since they are cheaper and more efficient on gas, or more preferably, an electric semi-auto pistol, since they'll perform okay all-year-round whether it is hot or cold. At a push you can use a cheap cock and fire springer pistol, but it's slower and not ideal, although they do have the virtue of being reliable and inexpensive.
A plastic knife is also a good thing for CQB, since although you can touch someone with your hand and say 'knife kill' at most sites, and it will count, one thing you cannot do is throw your hand, whereas obviously you can throw a plastic knife, and as with a BB, a hit anywhere on someone with a thrown knife will count as a kill. Make sure anything you do buy has a bendy plastic/rubber blade though, or you will not be able to use it.
Similarly, grenades can be a game-changer in CQB. But be sure to check with your regular site as to which kind are permissible (typically that will be BFGs - blank firing grenades - but check anyway). they can be pricey, so make sure that if you do get one, you don't get one that is something you cannot use at your local site, for example, some pyro grenades cannot be used at sites where there is combustible material such as curtains in the place.
If you get a tactical vest or webbing, be sure to get something that you can easily open and close the pouches on when it's cramped and dark (as it often is in CQB). Practicality wins over cool looks every time. Ebay and Amazon are the place to look for inexpensive ones. Worry about getting cool top notch crap later on.
Get a small portable torch. You can mount a tac light on your weapon, and that's a good idea in CQB, but a small torch is also good to have for things like reloading and such.
Make sure you wear full face protection and cover your neck, a helmet is good too, but a baseball cap will suffice. You will take more hits to the head than anywhere else in CQB, and at those kind of short ranges, even a sh*tty cheap springer pistol will fire a BB fast enough to smash a tooth out. An Arabian Keffiyah (shemagh) scarf will provide good neck protection, and you really do want to cover your neck, because a BB hit on your Adam's Apple will make your eyes water, and it will also draw blood.
Take a small water bottle, even in winter you will dehydrate when running and diving about all over the place.
Consider knee and elbow pads. CQB sites invariably have hard concrete floors, and that will hurt your knees if you kneel down behind cover. failing that, consider wearing long johns under your combat pants, they will help to stop hits hurting so much, will keep you warm in the present winter and will also provide additional protection from hit, bumps and bruises.
Gloves are not a bad idea too. Your hands will take hits, since they are generally exposed to fire because you are holding your weapon with them, and a BB hit on the fingernail in cold weather will hurt like a motherf*cker. Any old thin leather gloves from a cheapy shop will do, but make sure they are a snug fit so that you can operate your weapon's safety catch easily.
Hope some of that helps. You'll be an old hand in no time, but when it comes to buying gear, think carefully and don't let your heart rule your head. Almost everyone who starts out ends up buying some crap that they later don't use or regret having bought, so be sure to ask on this site if you are unsure about whether anything is a good or bad choice. Airsoft gear may not be free, but good advice is, and there is plenty available from the people on here.
Have fun and enjoy it. It's a really cool hobby to have and one which will let you do many cool things.
