How do you write a monologue?

Question

I need all the facts

Answer 1

You start talking to yourself and write it down.
or You mentally put yourself into the person who is speaking and write down what they are saying.
When a play for several characters is written, the writer must see the play going on and play all the characters in the mind's eye, shifting between characters with each step of the dialog.
The same thing in a monologue, except the transitions are changes of tone or thru line of thought

Answer 2

You decide on a topic. And then you start talking about that topic. Pretend that you will be speaking to a room full of people as you write it, usually requiring some sort of feedback from them (boos, hisses, laughter, etc). You should always have good pacing for a monologue as well. You have to keep people entertained with it, so it has to flow smoothly.

Answer 3

You have to be a character and write a story from their point of view. Like if you the wolf from little red riding hood, you wouldn't know that red is going to her grandma's until you talk to her. So it would go something like, "One day in the woods, I saw dinner skipping and picking flowers. I noticed she carried a basket, it smelled like cake and hot soup, appetizers..."
Good Luck and be creative.