You should pass on the job completely and have your friend contact someone who is good at doing these things.

The last thing you want is to be paid for a job you
1) Cant complete properly, take forever to do or
2) You come to dread working on as you are not competent.

Yes, you can improve your skills in these areas, but not on someone else's dime who is paying for skills that you don't have!
Work on your own websites/socmed and get good at it, then maybe -- if this is something you want to do -- you can market your services. Having no past clients is better than having unsatisfied past clients who will spread word about your bad work.