Newmar has different configurations from coach to coach, but there should be a height adjuster, near the outer edge of the slide at both ends. Double nutted stud, loosen the double nuts and then adjust the stud, lifting that end. Bring the slide in and match the paint work. It may take a couple of tries.
Don & Mary
2019 Newmar Dutch Star 4018 (Freightliner)
2019 Ford Raptor