Melchoir - I forgot to answer this. There are whole books about chi/kundalini, how to use it, breathing and movement techniques, etc. Books that I recommend are "Light on Pranayama" by BKS Iyengar, and "Science of Breath" by Ramacharaka. I'm sure others can make great recommendations.
In simple terms, think of chi as our body's electric current that stays mostly in our base chakra until we invite it to move into the other chakras (i.e. up to the 6th/7th to access the Records). When we have no internal conflict left, the chi will move freely between all the chakras. When we have conflict, the current will be weak where we have conflict (i.e. can't ask for what we want - throat chakra not open completely). When the first 6 chakras are allowed to freely express, the chi moves freely and expresses in the 7th chakra.