Could I use onto and in? (not in and on)
-They will have to post __ the assigned area __ Greenboard something.
Greenboard is the name of an online system where you will be able to find information about courses that you have registered for. Normally I would say onto in collocation with area is wrong and in should be used, but I guess maybe it depends on what that 'something' is and onto could be correct with area.