Stand parallel to the bench/box. The leg closest to the bench/box will be the one you are working! Hold dumbbells in your hands, step one foot on the box or bench and press through your heel to step up, slowly step back down and repeat - you can do all on one side or switch back and forth between legs.

Weight Recommendations:
Beginner: bodyweight-7lb dumbbells

Intermediate: 10-15lb dumbbells
Advanced: 20-35+lb dumbbells

*Modification: do this without weights!