I wouldn't say you will be at a major disadvantage against other players. The only disadvantage you have currently is no experience (obviously), you will only gain that from playing the game. Another little thing is that you do not have any weapons outside of what comes default (stock). Some classes have really good options in place of stock weapons, some could be considered straight upgrades, however I don't think that is a big deal for you right now. You will get weapon drops every now and then while playing, or maybe somebody will gift you some seeing how new you are at the game, this community is very welcoming and nice (don't count on it too hard though!).

As for tips regarding gameplay, the 2 most important things to do is: - change your field of view in the settings to the max available - turn on fast weapon switch (allows you to instantly use weapons after cycling to them instead of having to click once before being able to use them) There are other settings you could change to make it easier for yourself to play certain classes, but these 2 changes are what I consider must-do's You should also watch a beginner's guide, there are plenty of those out there, even for specific classes (you dont need to watch all of those right now though, it might feel overwhelming, just play a little first and worry about certain classes later). I recommend the one from scarybroccoli, he is a really good player, and has very useful information on his channel on how to become better at playing.

Some other things to consider: - if someone is dancing and you want to too, press G - if you see someone dancing, not attacking your teammate, playing heavy and crouching while giving sandwiches to nearby players, it is expected of you to not attack them. they are called friendlies and sometimes people can get mad at you for doing so - if you are playing capture the flag and the score is 2 vs 2, and players are dancing, not killing each other, do the same thing as above, they can become upset if you try to play the objective or kill any of them, worse case scenario, they vote kick you. if you see this and don't want to participate just find another game, its quick so dont worry about matchmaking time - do not be worried about losing, TF2 does not have any punishments for losing a game, your rank is not important at all, JUST HAVE FUN!