So I was accepted to Carnegie Mellon’s Class of 2021 (YAY!), and CMU is my top choice school out of the five that I was accepted to. However, the cost is still way more than I can afford. They only gave me about 5,000 to cover the total cost of about 70,000. 
I want to appeal the financial aid decision, but I know close to nothing about how this works, as well as the specifics to CMU. Can anyone help me with this and/or give me tips on the process?? Any help is much appreciated!!
Sounds like your parents have a high income. What is your EFC?
What is your basis for an appeal? Unless your family finances have changed any appeal will be denied. CMU determined that your parents can afford to pay the difference so they will have to make the sacrifices or you will have to attend another college.
Does it line up with the NPC? What were you expecting?
Look on the financial aid page and there should be a form for appealing decisions and has some choices for basis of appeal - lose of job, illness, death of a parent, etc. If you want to appeal merit aid, usually that has to go through the admissions office.
IIRC, CMU only meets 100% demonstrated need in the ED round. Carnegie Mellon states that they do not meeti 100% demonstrated need.