I have a set of ford mud flaps for the back end of my 1995 ford f150 xlt but I'm not sure how to mount them ?

 

 

This are the mud flaps I have the front are easy to mount but I am not sure how to mount the back flaps.

 

The best way is to have two people. Put some dabs if grease on the places where you want your screws. Have someone hold them while you stand back and make sure they are straight. When they are positioned how you like them, have your friend press the mud flap against the fender or bed. The grease will mark where your screws will need to go and where you may have to drill. If they are heavy, add some supports if possible.