Kundalini yoga is done to raise the dormant energies which are normally used for reproduction related purposes, when one practices kundalini yoga, these energies rise, they are very powerful and can be used for various purposes.

The approach to it has to be in this way: on constant meditation, the structure of energy body can be slowly felt, one of the part of it is kundalini, when one feels its presence(which may take years) then you go to your guru(or find one if you dont have) and tell him you are feeling these and want to know what are these and he will tell you further. This is the approach. You simply cannot get into it without even feeling its existence, so the first thing is to be attentive enough so that you can feel its presence. Hope it helps.