A poker bankroll is an amount of money set aside for poker, which will not be needed for other purposes. Bankroll management means to game select in a way, so that the risk of losing all the bankroll, or a substantial part of it, is reduced to an acceptable level for a long term winning player. This also mean, that if you are not a winning player, it is not even possible to have a poker bankroll.
Lets say you go in a casino and play the classic
roulette with 36 numbers. You bring $1.000 with you, and now you need to decide how much to bet at a time. If you put all $1.000 on "red", there is a 51,35% risk, that you only get to play this one time. The odd number is because, there is a blank slot, where all players lose, and the house wins. This is the cut taken by the house. In poker we call it rake.
If your goal is to have a whole evening of fun,
gambling all the money on the first run was bad money management. It would have been wiser to only bet maybe $50-100 at a time, so you could afford to lose 10-20 runs before being out of money. But no matter how conservative you are, unless you stop playing, you will eventually always run out of money. This is, because your long term ROI (return on investment) is -2,7%.
Now imagine that it was the players, who won on the blank slot. Then your ROI would be +2,7%, and now it would suddenly be possible to have a bankroll and talk about bankroll management for playing roulette. In poker it is possible to have a positive ROI, unless the rake is unreasonably high, or the structure of the games very poor. This is, because there is a skill element to the game. And therefore the answer to your question is, that in the beginning its most important to focus on improving your strategy and gain experience, because thats the only way to achieve a positive ROI.
However when you have a track record of say at least 1.000 tournaments, that are not freerolls, and you are winning over that sample, THEN it become important to implement bankroll management. This is because, if you run out of money, you can no longer play. And if you are good enough to beat $10 tournaments, its also not desirable to move down to $1 tournaments or freerolls, because you lost most of your bankroll.
If you have only played for 2 month and now have a bit of money in your poker account mostly made from freerolls, its really not advisable to consider this a bankroll or try to manage it as a bankroll. The best option is to make a reasonable deposit and try to manage that, as it is was a bankroll. Could be $100 for SnGs or cash games, and if I am honest not much less than $500 for MTTs. If this is not an option, then I would try to fix first, whatever prevents you from making such a deposit before spending any significant amount of time on poker.
If you really insist on "building up a bankroll from freerolls", which I think is a very poor plan for several reasons, then you should manage the money in your poker account, like you would manage the $1.000 going to the casino to play roulette. Your goal is to get experience, so if you have $20, you dont want to spend it all playing a $20 tournament.
But you also dont need to think about the risk of "going broke", since you can still add to the bankroll by playing more freerolls. Which mean its not really a bankroll but more like a budget, until you get the next freeroll cashes. So maybe its fine to play $1 tournaments. Then you can at least play 20 of them and hopefully more, since you are likely to cash a few times during those 20 games.
