The "Theta state" is just a more scientific term for a meditative state. It describes the dominating brainwave pattern (Theta). When we are in our normal awake state during daytime, the dominating brainwave pattern is called Beta brainwaves. When we for instance sit down, relax deeply and let go of our daytime worries, the brainwave pattern slows down and goes one step down into Alpha. If we continue to relax and start daydreaming, or we lay down to sleep, the brainwaves slow down even more into the Theta state. People who do meditation put themselves into this state and remain there.

While in this deep state the outside world doesn't exist to us. Our concept of having a body etc starts fading out and we purely exist in a more expanded state of awareness. The brain increases the production of those feel-good biochemical substances like serotonin.

After a while we gain a larger sense of being able to do what we want in that expanded state, just like when having a dream in which we are awake. With intent, we can from here gain knowledge about things, remote view locations in space and time and communicate with other beings who are also aware in the Theta state.

We can hear music, see fantastic things and get ideas, solutions etc which we can then bring back with us to our awake state, for use in our lives. In the Theta state these things come completely without effort, presented in its full scope, all at once like it is dropped in our lap. It is an expanded state in which our abilities are virtually endless.