Priest listens carefully as you begin your explanation while stroking his chin. It has been a long time since he had to teach genjutsu to a student since Taijutsu has been his thing. However, he is still a genjutsu master and would not fail to notice some error in his student's analysis, likewise his reason for wanting to learn genjutsu.
First off, you mentioning genjutsu through the eyes means you are already deviation from what you are here to study. Eye genjutsu is sharingan genjutsu so it'll be best if you don't refer to them among the genjutsu you'll be learning although during the course of our training session, we'll make mention of them.
Priest puts you in a genjutsu where you see yourself in a room, already sitting as if you're in a classroom and Priest begin to write on a giant white board.
Genjutsu creates Illusions.
illusion means "an erroneous mental representation" meaning "false reality"
When we say genjutsu, you should put few points in mind.
-Chakra
-Forcing chakra into your target's brain
-Using the chakra to disrupt the target's chakra flow, disrupting the balance between his physical and spiritual energies
-taming the senses
-planting the illusion using the senses. This is like writing a temporarily and virtual program that hacks into the target's mainframe and takes control of the target's senses.
Now lets treat them one after the other.
-Chakra: You will mold your own chakra and transfer it towards the target.
-Forcing the chakra into the target: You will force your chakra into the target's brain. This and the first are somewhat known to happen instantly. However, you do this, you have to see your target or have a perception of him, pinpointing his location. This is because, forcing chakra requires precision and advanced chakra control and having no knowledge or perception of the target makes you unable to carry out the process.
-The third is quite understandable. Your chakra entering into the targets chakra network, disrupt his chakra flow. This cannot be seen though or directly noticed except when the chakra pathway is viewed with enhanced visions like the doujutsus and chakra sensory.
-The above gives you access to the target senses which you can make to dance to your tune. There are 5 senses in all that can be manipulated. "Smell, Sight, Hearing, Touch and Taste"
-Lastly, you can now manipulate the senses in such a way you deceive the target into believing something that is not real. "false reality"
Taking the sense of smell for example. You can tame the target into perceiving a sweet smell to be sour or spoilt. Very useful genjutsu against the inuzukas if you get what I mean.
More than one senses can be tamed at once.
Priest stops writing and turned to his student within the false realm.
Before we proceed, I want you to assimilate and understand what was written. If you don't understand anything or if you need to clarify anything, you can ask question.