What is going on in The Office?

I see that in some episodes Ryan is Mike's superior, what happend there?
Why was Jim sometimes at another office?
Why is Jim now back with one of the Stanford people?
When did Mike get together with Carol instead of his other girldriend?

And what did Jim get promoted to?

At the beginning of Season 3, Jim transferred to the Stamford, CT branch to get away from Pam because she was getting married to Roy. The Stamford branch was going to be the main branch and the Scranton branch was going to close but Josh, who was the boss in Stamford, turned down a regional management job because he took another one at Staples. So the Stamford branch closed and the employees from there, including Jim, came to Scranton. At the end of Season 3, a position opened up in corporate for what turned out to be Jan's job. Jan was fired and both Michael and Jim withdrew their names from consideration leaving Ryan as the one who was hired. Thus, he became Michael's superior. Carol dumped Michael in the Christmas episode in season 3 because he was creeping her out as evidenced by him superimposing his head over her ex-husbands head on a family ski vacation photo. He has been dating Jan ever since. Also, while Jim was at Stamford, he dated Karen, but dumped her at the end of season 3 and now she is the branch manager in the Utica, NY branch. So there you go. :)

oh dear, you are really behind.

they started season 4, but because of the NBC writer's strike, they're playing episodes from season 3.

so i'd say watch all of season 3 in order to catch up, and then maybe by then season 4 will be back on.

You should watch the last season to catch up before new episodes come out.

Ryan's Michael's boss because he was hired for Jan's job. A lot of people were competing for it and interviewing in the season finale.

Jim was in a different office at the start of last season because he took a job in another city to get away from Pam.

Jim and the others are back in Scranton because the Stanford boss quit. It's a bit more complicated than that, but that's the gist of it.

Michael's with Jan now. He has been since mid-last season.