Hi Cdmom. You're so lucky you'll be at WDW soon! (I just got back but I always want to go again!)
FP can be used by anyone with a ticket to get into the park. When you enter the park, grab a park map. It'll list all of the rides in that park eligible for Fast Pass. When you get to the queue area of the ride, you'll see an overhead sign that lists the return time for FP's currently being given out. For example, you may go over to Splash Mountain around 10:00 am and the Fast Pass return time will say "11:15-12:15." This means that if you get a fast pass for that attraction right now, you'll be able to return between 11:15 and 12:15 and go through the fast pass line. Depending on the ride, this will mean a 5-10 minute wait.
To get the FP, you enter your park ticket into the machine. Your ticket will pop back out as will your FP, which will have the return time on it, as well as the time that you can get another FP. This is probably the most confusing part. In general, once you get an FP, you cannot get another one until the time for the first one starts. Staying with my example from above, you would not be able to get another FP for any other FP ride until 11:20 (5 minutes after the start time). However, if that FP is more than 2 hours away, you will be able to get another FP in two hours. For example, it's 10:00 am. You get a FP for Test Track for 1:30-2:30. You will be able to get another FP at 12:00.
The standby line is the regular line. It's the same line that has always been there for years and years. They just call it the standby line to differentiate it from the Fast Pass line. You will see a posted wait time at all rides (FP or not) for the standby line.
One other thing to note, each person that wants to ride and be in the FP line will have to get a FP.
Hope that helped.