The main session is Yasso 800:

You first need to know your marathon goal time in hours and minutes. Then, convert this time to minutes and seconds. For example, if your marathon goal is 4 hours and 30 minutes, your converted time is 4 minutes and 30 seconds. Once you have your time, follow the below training schedule:

Warm-up
800-meter interval: Try to run 800 meters at your converted time (4:30 in this example).
Recovery: Jog or walk for the same amount of time (again, 4:30 in this example).
Repeat
Cool down/Stretches

Other sessions may be available