Lay on an incline bench.
Grab the dumbbells with a pronated (overhand) grip. You can do this exercise thumbless if it's more comfortable on your wrists.
Flex at the elbows until your biceps touch your forearms. Try not to let your elbows flair outward.
Guía de Ejercicio Dumbbell Incline Reverse Curl - Entrenamiento de Biceps | MuscleWiki