I dont know my grandmas name or last and i need it in order to start tracing my bloodline to prove im cherokee?

i dont know how or where to go to find my grandmothers name and i cant get it from anyone else i dont have any family she died around when i think when i was 3 i dont know her birth date or death or where she was born nuthing i know my moms last name and first but i dont know her birth date but i do know my dads birthday last name and first and where he was born but my dads mexican the cherokee comes from my moms side of the family out in georgia where i was born im trying to enroll my self and prove my bloodline but i dont know how to get started and i have no money ....... i tried doing it online but every website that says its free ends up not bieng free how am i suppose to do this is there anyone i can call or write 2? and i dont know what tribe my family is from either or if thier listed or not but i do know i have enough cherokee in me to be considered one too and im not claiming anything i just dont have any proof and thats y i need to know so i can gather some proof so plz help id really appreciate it