See how-do-membership-levels-free-vs-premium-affect-access-to-tournaments.
If the 1400-1600 and 1600-1800 are official tournaments, you will automatically be transferred to the corresponding 1600-1800 range (if your rating has changed).
Withdrawals are counted so that future TDs can assess whether someone is worthy to stay in their tournament. 
Thanks Artfizz. I'm now registered for the 1600-1800 section.
You can play in all Chess.com official tournaments plus one other.
Really? How about team matches, are they tournaments too?
Just a few days ago, I'm playing in chess.com Quick Knock-Out 1600-1800 section (10 simultaneous games), playing in team match (2 simultaneous games) and registered for a user tournament (King's Gambit).
I wanted to join a tournament that was about to start (10 players out of 12, 1800-2100 tournament) but I couldn't, so I withdrew from the chess.com tournament, but still unable to join the new tournament. But at last I was able to join the new tournament after withdrawing from my registration in the King's Gambit tournament.
May be I didn't need to withdraw from chess.com 1600-1800, but just withdraw from my KG tourney registration in order to join another user tourney. But, well, the second round of the chess.com tourney will not start in 2 months anyway so why should I stay.
The new tournament is very fast, only one round with 22 simultaneous games. And with tight competition (1800-2100) it is more useful to me. It was a good decision to withdraw from a multi-round tourney (after completing all games in certain round) and join a new one that is just about to start. A tip for non-paying members.
Really? How about team matches, are they tournaments too?
Just a few days ago, I'm playing in chess.com Quick Knock-Out 1600-1800 section (10 simultaneous games), playing in team match (2 simultaneous games) and registered for a user tournament (King's Gambit).
I wanted to join a tournament that was about to start (10 players out of 12, 1800-2100 tournament) but I couldn't, so I withdrew from the chess.com tournament, but still unable to join the new tournament. But at last I was able to join the new tournament after withdrawing from my registration in the King's Gambit tournament.
May be I didn't need to withdraw from chess.com 1600-1800, but just withdraw from my KG tourney registration in order to join another user tourney. But, well, the second round of the chess.com tourney will not start in 2 months anyway so why should I stay.
The new tournament is very fast, only one round with 22 simultaneous games. And with tight competition (1800-2100) it is more useful to me. It was a good decision to withdraw from a multi-round tourney (after completing all games in certain round) and join a new one that is just about to start. A tip for non-paying members.
Right, you could have stayed in the official one. As a free member (even a gold member, with only 10 tournaments), you should pick your member tournaments carefully. I always try to find smallish (12 players or fewer) 1 day, no vacation tourneys, so that I dont have to wait months or years for tourneys to complete.
Team matches are not tournaments.
Thanks for the tip, rooperi. 10 tourneys looks like a lot of games to play.
I just learnt that (after playing 25 simultaneous 1 day/move games), playing online (correspondence) games is not bad at all when the games are plenty. It's easily become a standard blitz "time control" (in term of time used to think) with the benefit that you can think longer time in critical positions and will never run out of time 
And it is very productive playing it that way. You may lost a few games (compared to those who play only a few games) but you will learn more imo.
I believe it is another tip (for chess training) I have never read before (the benefit of playing a lot of games in correspondence). And I always replay the moves from move#1!! 
I cannot find the rule so here is my situation and asumptions:
I have just started a few online games so I can join the tournament, especially the quick one (unfortunately that 1 day per move is the quickest). My rating now is 1582 so I need an open tournament. If my games end sooner before July 1st (I have 2 winning games) my rating would go up above 1600. So if this is achieved my plan is to withdraw from 1400-1600 and join the 1600-1800 Quick Tournament.
After some thought, even if my games would not end before July 1st (so cannot go above 1600), I would still withdraw from 1400-1600 and wait for a beter tournament, asumming that as a non-paying member I can only join one tournament.
After some more thought, even if I can join more than one tournament, the games will be too many. Many will be of low quality, and I have just not enough time and energy so I will withdraw from 1400-1600 anyway.
Now, why is the number of withdrawal recorded? Will there be a negative effect?