Each week (on Tuesday's) you will receive an e-mail from Jonathan with a Weekly Assignment and Video. This e-mail will tell you what you need to do for the assignment and give you the link to the video to watch. When you have completed these, you will keep track and assign yourself points under the "Track Progress" tab where "Weekly" is.
You can find the Weekly Motivational Videos under the Recorded Workouts page or under the Personalize Motivation tab under "Videos".
You can also see the Weekly Written Assignment along with all the other Daily Missions under the Community tab in the "Daily Missions + Weekly Videos & Written Assign" forum section.