The story starts at the end of 3x14, with the Original Witch having just bound her children as one. From then on, it is up to you to decide where things will go.
Of course, you can have completely off-topic and crazy threads if you want, as well as threads that take place in the past.
Every once in a while, there might be an event, most times following an even that actually happened on TVD, such as a party, that will affect the whole forum. Some might just affect a certain group of people, such as school ball, and some might really affect everyone. They will be marked as announcements.
If you have any questions about the plot or anything else, just post them in the questions thread.