To compress the energy on itself, you would mentally and emotionally pressure the energy to fold in on itself, like clamping down on it from all sides or from various angles which it is trying to escape from.

At first one cannot do this but what will happen is that one will find that when doing kundalini yoga, sometimes in a small part of the psyche somewhere there is a burst of energy which is so small that one can easily control it with a mental or emotional squeezing action.

Then one should squeeze that to its center and keep squeezing it until it reaches a stage where it bursts out. In some cases pushing up or pushing down will also cause some energy lumps to move here or there and when it tries to move if you block that mentally, it will then compress in on itself.

This practice begins with pressuring down from the navel down and then pushing across from the groin area to the base chakra. Instead of just physical locks, it will transform into mental locks.

Please note that I missed your inquiry before and just noticed it because Surya decided to deal with this and it was on the top of the list. In the future please send me an alert if I do not reply to an inquiry. Thanks!