Apologies if any of these explanations seem ambiguous or confusing sometimes. Some things are hard to explain in words.

At the neurological level, the process of thinking is practically a series of electrical discharges. Remember The Matrix movie? Obtaining electricity from people’s brain activity?

More or less, this is what happens at the psychic level of controlling energies as well. Focusing the thought(s), will be accumulating energy. The control and manipulation of this energy is the "basics" of doing magic. The greater the ability of focusing, the greater will be the ability of controlled manipulation.

Nevertheless, the focusing part is the hardest part. This is why so few reach true initiation. Try, for at least 10 seconds, to focus on one single thing, inhibiting your senses, to the point of not receiving physical information (sounds, touch, feelings of cold, itches, etc.). If you manage to do that, then you are able to reach the state of "pure emotion" that only Initiates are able to reach. Focusing (concentration) techniques are nothing else than mental discipline exercises.

If you can reach the state of "pure emotion" focusing, you then can learn how to draw more energy, how to channel, control and direct it. The intensity of this "energetic flux" can reach astonishing levels and force.
Energy can be drawn from our surroundings, from our level of existence. But the next level of energy manipulation brings you even further. That would be to learn how to draw it from the "other planes", by opening portals and communication channels. This can be done in various ways: rituals, invocations, summoning, contact persons (mediums)  even entities taking over the body of someone.