How do you overdraft your bank account?

Yes i know, stupid. But I NEED the money. My cars gas is on empty and i dont get payed till friday! I dont care about the overdraft fee. Ill pay it. But i tryed getting money out at my banks ATM. but it wont let me. I know people do it. But Im not sure how?? Someone told me to go to another banks ATM and theyll let me do it? HELP PLEASE! THX!