We have lots of resources on our blog that may answer your question. If you can't find the answer there you can try these forums:
Many GRE and GMAT questions have been asked and answered here. Simply type in the first several words of your question and see what comes up! You can post your questions there as well, and most likely have it answered by another user.
If you have some time to wait for your answer, send our tutors your question using the purple Help tab. The Magoosh office is located in Berkeley, California, so while some of us might be asleep when you send in a question, we'll respond as quickly as we can! We also have tutors working in many time zones, so you may get a response within a few hours :)