Stage 2 kegel balls.
Heavier and longer than single ball.
Stage 3 kegel balls.
Heavier and slightly longer than stage 2 set.
Add some lubricant to the kegel ball.
Open your legs, relax your vagina, push the ball slowly into your vagina.
When comfortable you can do some exercise, like walking, swimming or doing house work etc. The internal metal ball will collide with the inner surface while you are moving to cause a pleasing vibration.
Clean it before and after use with soap and warm water, then let it dry naturally in the air