I can understand the visualizations being a little difficult to perform but don't stress too much on it. As always, feeling the runes and the intention in your vibrations is what's most important.
Proper visualization comes with time.
But to give you some easy interpretations, the Runes when vibrated, like any energy can invoked or evoked. The energy can be received or given. So as your vibrating the Runes, you can visualize that from your aura, you are sending energy to the entire Shenu Ring. The vibration you feel from the Runes, you are sending to the Ring. You're focus while vibrating can start at the center, and then expand around the Ring as you continue.
With time, you'll be able to let your creativity come out and have fun with the concept of, "glowing up" the center of the Shenu Ring. But for now, this is just to keep it simple, and I hope it helps.