“I started to meditate 2 weeks ago and 1 week ago started to meditate on chakras.”
Concentration on the chakras is not meditation, but it can be used as a method to enter into meditation. There are eight depths of meditation, and once you come to the first, whatever was your object of concentration - whether a mantra, yantra, or a chakra, it disappears. Meditation cannot be done as an effort of the mind.
“2) I heard that some people got traumas or gone insane, because they meditated on chakras in wrong way, is that possible?”
Yes. First it is important to understand that these chakras are also different aspects of one’s own consciousness. The lower three chakras are corresponding to instinct, the heart center to your emotions, the throat more with the intellect, ajna with the intuition, and sahasrara with the direct experience of one’s true nature, or what has been called nirvikalpa samadhi.
What you are doing through concentration upon the chakras along the spinal cord, is that you are awakening different aspects of your own consciousness. Different states of consciousness are different states of energy, and the chakras are simply centers of energy in different states of vibration. And the problem is that our system is so complex, that any change in any part has an influence on all the other parts, everything is interconnected. That is why, if you are going to do work with the chakras, it is not something that is to be done radomly, but in a systematic way. One has to first start from the root chakra, bring certain qualities of energy into it before working on the other chakras until eventually one’s energies reach sahasrara at the top of the brain.
If the work is not done in this systematic and scientific approach, it can create more damage than good. There are people who have become psychologically insane because they awakened certain energies in their system which they were not able to handle, all kinds of mental disorders can arise from improper practice. This is why in the yogic sciences, all of the methods dealing with awakening certain energies in the subtle body and spinal cord, have always been transmitted secretly to ensure that such things would not happen. If one is practicing these methods without the proper understanding, rather than assisting you towards your enlightenment, it can only take you into an even deeper unconsciousness.
“3) I meditated on chakras 6 or 7 days and it feels good, but now I’am scared, please give Me some advices”
The danger lies not in not knowing the method to awaken these centers, but in knowing the method and being successful at it. If you do not know of the techniques, then there is almost no possibility of such problems happening : )