Financial fair play rules

January is almost here which means the window will open to bring in New players.
Can someone please explain the exact position we are in with the rules .All I here is we have to juggle things to off load players to bring players in .I no we had to adjust coming down from the prem but to me it seems the club just can't get the Ballance right in terms of who is a good player and how much pay out on them .Marshall leaves we bring in Lambert on high wages we all no the club hasn't been very shroud over recent years so what is out current position financially and what can we expect in January and into next summer in terms of how much we can spend.also be interesting to no how we compare to other clubs in our league.
Can someone explain it all ?