To create a guide like this, just follow the steps below.

First you need to decide on a game or other software from the steam store for which your guide will be published.
I decided on Steam: https://gtm.steamproxy.vip/sharedfiles/editguide/?appid=753

Then you need to decide on a Title. This title should represent what you are trying to convey to the audience of your guide.
I wanted the Title to be blank so I used this character:
(Don't worry: If you drag you mouse over the line and press ctrl+c afterwards it will copy even though it's not marked)

In this step you will have to decide on a picture that's representing your guide.
I decided my Guide isn't really graphic so I don't really need a Picture.

Now you will have to create the content for your guide.
This content should be:

• well structured.
  
• easily understandable.
  
• appropriate for the audience it is reaching.
  
• usable in the software it is created for.