The final basic Tantra Exercise, which when learned can be combined with the Breath and the PC Pump, is the Pelvic Tilt. It's not the easiest thing to explain in print but I will give it a try.
I have found that the easiest way to learn it, so that you can get the sensation in your body, is to lie down on your back with knees bent, feet flat on the ground. Focus on the area right above the cheeks of your butt. In the center of your body there, is a bone that is a triangle called the sacrum. This is where you focus.
Usually when lying down in this position, there is a natural curve to the back, with this triangle,or sacrum, slightly arched, leaving a space right above it between your back and the floor. To get the motion down, tighten your thighs a bit and flatten only that sacrum part of your lower butt/back to the floor. Don't round your whole back, just that part moves. Now press it under a bit more, arching the pubic bone up and tilting it at an angle. Then release and arch it the other way slightly exaggerating the space between the back and the floor. Again...this does not involve the whole back, just that sacrum area. Try it a few times, then when you feel comfortable, do it rhythmically to a very slow beat, arching first one way then the other.
Once feel you have the sensation of what it is supposed to feel like with the added pressure of the floor, you can then sit on a chair with no arms. Sit up straight on the edge of the chair, spread your legs and begin the motion in that position. Again..all movement is just in that lower part of the body- only movement below the waist should be going on. You can imagine that your pelvis is on a fulcrum moving back and forth while the rest of the body sits still.
And once you have this down, you can practice it in a variety of positions, always focusing on isolating that very lowest part of your body. Eventually you will feel so at ease with this, the Breath and the PC Pump exercises that you will be able to combine them. I'll talk about that some other day in another post.