I borrowed my dads car while hes out of town and ive never rode in it and i dont know how to open the gas tank u cant do it from the outside so help!!!

If I recall correctly, the fuel filler lid is tied to the central locking system. So when you unlock the doors, the lid is unlocked. THen all you have to do is press in on the door on the hinge side (towards the front of the car) and it will pop open. It's not like a japanese car where there's a lever to pull.