Start with the front side of the fender.
The 2 screws are different lengths and the front screw should be the longer one.
I get the fender and headlight aligned and thread the front screw in just enough to keep the screw in place.
To get easier access to the rear screw, turn the handlebars/fork to the side.
Then get the rear screw installed most of the way. Sometimes you have to push a little bit to get it to work.
Fully tighten the front screw keeping the fender and headlight in proper alignment.
Then finish tightening the rear screw. Be sure to double check the alignment of everything.