The Mk1 Cock Ring should be worn around the whole package (penis and testicles), sitting flush with your pubic area. The small circle on the Mk1 should be at the top and facing backward, towards the body.
In this orientation, the contour at the bottom of the ring should curve under the body and hug the perineum.
If you're having trouble putting on your ring, we recommend getting one testicle through at a time and inserting your penis last.