auras or chakras called by the eastern.
aura is the display of a protective energy of one's soul. Dependent from the bearer it varies color, intensity, and size.
yoga helps aligning the chakra points to develop them.
you just need to breath in energies
(how to breath-in energies?)
if you aren't familiar with it just visualize that every inhale you do there is this luminous mist/fog that gets in through your nostrils, then visualize it passing through all the upper chakras (the crown, 3rd eye etc.) when you exhale visualize the absorption made by your soul. this will expand the aura.
must develop 3rd eye to see through the color though..