To add, I think your best resource to tackle your assignments will be your course instructors and TAs. I'd poke them for the resources you need to be successful in your class.
In terms of finding tutors here, I don't think the instructors andresrcs recommended will be helpful, since they tend to be instructors focused on teaching larger classes for companies.
This forum may be a good place to get help. I'd suggest two things:
- Get to know our homework policy. There are a lot of R educators here, and you don't want to run afoul of how your instructor prefers to teach your course - FAQ: Homework Policy
- As mfherman suggests, feel free to ask specific questions you have here. What's a good way to do that, you ask? That's a great question and I'm glad you asked, FAQ: Tips for writing R-related questions.