You can get help as long as you have an IEP (sounds like you should already). The help you get though depends on your needs stated on your IEP. You will need to have an updated IEP sent in when you register, along with the evaluation that was done first. Jump on this Though and get it done soon. Talk to someone at your school and they can help you. You MOST DEFINITELY should have accommodations (help on the test).
I found this site which seemed to be helpful, perhaps an adult can go over this with you so you can understand what YOUR rights are for this test. It shows you could have an audio tape for testing, but it depends on your diagnosis.