These symbols are not "secret" (though I do know a few Reiki Masters who believe that they should be), but they are to be kept sacred. This is not because they hold some secret esoteric "power." They don't. The only power the symbols have is that which you lend to it. They're just symbols... a tool used to focus the Reiki energy. 

In order for these symbols to work... to be of use to you... you must be attuned to them. The same concept would apply if I were to hand you the alphabet, written on a piece of paper. Unless you know how to use this "tool," and know what to do with the letters, it's useless knowledge. However, once you do learn how to make use of this thing called the "alphabet," it then becomes, as they say, "mightier than the sword." 

What transpires during the attunement is that you are given "control of" the symbols, and taught how/when to use them, which enables you to make good use of that symbol. By drawing the symbol, a body-mind-soul/spirit connection is made. 

As mentioned earlier, the first symbol taught in Reiki is the Cho-Ku-Rei. As to when this symbol is given depends on the Reiki system, and on the Reiki Master/Teacher. Most Traditional Reiki Masters do not give any of the symbols during level one. It is my personal belief (and practice) that the Cho-Ku-Rei should be given during the Level I attunement, since this one is the "energy switch." 

The Cho Ku (Power Increase) represents honesty, simplicity, cheerfulness, correctness, return to normal, repair. Rei is soul, spirit, spiritual. According to Tibetan Buddhist teachings, the symbols' original use was not for healing (which is a "worldly" matter) but Enlightenment to help others. It is the beginning or entrance, generation stage. The first step, the first experience, and in "Reiki definition," the light switch. The Cho Ku Rei focuses on the physical body in healing.

In Traditional Reiki, the Cho Ku Rei is drawn counterclockwise, which is how I was taught. However, there's a school of thought in some metaphysical circles that the clockwise motion is the direction of invoking and increase, and counterclockwise is the direction of dispersion. 

In reality, this would depend on which Hemisphere you lived in. In the Northern Hemisphere, clockwise is used for invoking/increase; in the Southern Hemisphere, it would be counterclockwise. Therefore, pick one way and stick with it. For me, the counterclockwise "feels" more natural. The important thing is that the symbol (ALL Reiki symbols) be memorized and drawn exactly. 

• Use at the start of a healing session to increase power at each #1 position; head, front and back of torso, and on any problem areas.
• At the end of a session to seal in the healing energies. 

• To clear a room of negative energies.