Hi, Monica, I'll try and expand a bit on what MJ said:
Basically, MJ and AJ have the Virtual Seasons set up just like the original series. Most episodes always ended with the leap-in for the next episode, which is essentially the Prologue to the next episode (usually written by a different writer). What MJ and AJ do is decide where those episodes could fit into the season lineup, and they edit the leap-ins accordingly, in the same way that Don Bellisario did in the original series.
I'm also a relative newcomer to the Virtual Seasons, however I have recently managed to catch up over the past several months, so I can update you on a few details to keep in mind when and if you want to write for it:
First of all, the most obvious detail being that all stories take place after "Mirror Image," which means that Al and Beth are together and have 4 daughters.
Al also has another daughter with Lisa Sherman, who now also has a child.
Gooshie is dead and has been replaced by Edward St. John VI (NOT St. John V from "A Leap for Lisa," but his son).
Sam has an 8-year old son Stephen, with Donna, who was born 9 months after Sam's first leap in 1995.
And the evil leapers are sort of out of the picture now, however, other leapers always seem to pop up eventually. (In fact, there just might be a new character showing up this coming season that will turn Sam's world upside-down. *shameless plug*)
The best thing to do is go to the main site, click on the Introduction link, and then go to The Story Thus Far. That should give you all of the major events that have occured in the series so far. Not sure if the Ninth Season update is up yet, but it should be soon enough. Good luck writing!