We have devised problem set drills from the Official Guide books that you have. Where exactly you find these problem sets depends on which program you are doing - Interact? 6th edition regular course? 5th edition regular course?
It would be best to contact our Student Services team (800.576.GMAT from US or Canada or
gmat@manhattanprep.com), as they can see which program you are doing and direct you accordingly. (I'll also point them to this thread, but I think they're going to need to know what program you're doing in order to answer your question.)