How do I find my Server/User/Channel ID?

First make sure you have Developer Mode enabled on your Discord by visiting your Discord settings and going to Appearance.

To get your Server ID right click on the server icon on the left hand sidebar then click on "Copy ID" then paste it into your Discord or on a text editor.
To get your User ID or anyone else’s User ID right click on their name and click "Copy ID" then paste it into your Discord or on a text editor. Alternative type there name as a mention and place a backslash \ in front of the mention. It should look like this <@!357240408373198868> and the numbers are the ID.
To get a Channel ID right click the channel and click on "Copy ID" then paste it into your Discord or on a text editor. Alternatively type the channel as a mention and place a backslash \ in front of the mention. It should look like this <#475182341782896651> and the number is the ID.