Seeing a self in the moment is the first step. The second happens later, in quiet.
The books call it meditation on the ego. It sounds grand, but it is simple. You sit or lie down, relax, and go back to one scene where a self took over. Then you watch it again, slowly, as a witness.
You look at it the way page 18 described: its thoughts, its feelings, its body. You look at what set it off, and at the moment just before it took over. You ask what it wanted and what it feared. You notice which other selves came with it, because they rarely come alone.
Thinking about the self is a beginning. The books say it must also be understood with the heart. That kind of understanding has a feeling. It is quiet, sometimes a little sad, and very clear. You see the self for what it is: not you, and not something you need. When that feeling comes, you have understood.
An example
A woman snaps at her son over a spilled drink. That night she sits and plays the scene again. Just before, she was tired and late, and wanted one thing to go right. As the self took over, her jaw set and her voice rose. Asked what it wanted, it answered: order, now. Asked what it feared: that everything is slipping and no one will help. Seen like that, it is not her. It is an old impatience wearing her face. She writes one line: It wants control because it is afraid.
Two things spoil the work. Condemning the self makes you look away. Justifying it makes you stop looking. Stay between them: interested, kind and honest.
One sitting is rarely enough. A self has many faces and many roots. Come back to the same one for days or weeks. Each time you will see a little more.