Fender and door rubbing grinding together and causing loud POP!?

This is for my moms car its a pt cruiser if that helps at all but, my brothers friend was sitting on the front of the car (right around the driver side headlight) And when after that my mom went to open the door and it was stuck shut the fender was pushing against the door. we pulled the fender a little to get the door open it opened and we never thought anything of it but now it constantly pops and gets stuck and the paint is chipping in one spot where you can see its grinding together. does anyone have any ideas on how to fix this easily? It's not a big problem but very irritating and embarrassing.