Quote the previous week's plan. This helps you determine whether you accomplished your goals.
State this week's progress. This can include information such as: what you have accomplished, what you learned, what difficulties you overcame, what difficulties are still blocking you, your new ideas for research directions or projects, and the like.
Give the next week's plan. A good format is a bulleted list, so we can see what you accomplished or did not. Try to make each goal measurable: there should be no ambiguity as to whether you were able to finish it. It's good to include longer-term goals as well.