Abel, CCI is an unbound oscillator that like all oscillators attempts to put a finger on momentum strength. You can also set the horizontal signal lines within the CCI. I used to set mine at zero, + 113 & +225 and -113 & -225. I would use the CCI in conjunction with a Double Bollinger Band.
You can trade with it several different ways, from the zero line out or the outer signal line inward. As all indicators measure deviation from a mean I choose to trade from the +2% deviation inward. You would call this mean reversion trading. All price action will return to the mean.
Their is much information published about this indicator and several Youtube videos.
Timing Trades With the Commodity Channel Index