Where can I find more information about how FastPass+ works?
I’ll add a sticky. 
Just want to say that this system is terrible. But do use the recommendations from Bob and Len. They do a great job explaining how to take advantage of the system. The reason why I say its terrible is because you only get three attractions per day, and you can’t reserve any at another park until you’ve exhausted your current ones or the time expires. Also, if you’re a non-Disney guest, you make reservations 30 days in advance. Disney World resort guests can manage their tickets 60 days out. We could never get FP to the Seven Dwarves Mine Train, but we felt we didn’t miss out. The lines were uber long, and if it was a cross between Barnstormer and Thunder Railroad, we would much rather just do TR.