Hello there and thank you for your question!
MyPlate was created by the USDA as way to help Americans eat a balance diet. You may have seen earlier images of the Food Pyramid. MyPlate is a helpful because most Americans know what a plate looks like. What MyPlate does is give you a good idea of portions and that half your plate should be vegetables and fruit.
SuperTracker is similar to many of the fit trackers that are on the market. It can help you with counting calories and to track physical activity.
The two can work together because the foods you choose to track on SuperTracker should fit into the different portions of MyPlate. For example, say you cooked EatFresh.org's Simple Fish Tacos. At the bottom of the page is the nutrition facts for the recipe. You can plug in the info in SuperTracker and visually see if this recipes fits into all the areas of MyPlate. It does for the most part but I would probably add this delicious Apple Slaw to fill in the vegetables and fruits side.
So they can work together with one tracking your calories and the other ensuring you are eating healthy and balanced portions.
Hope that helps!