This page is a collection of userboxes, small colored boxes designed to appear on a user's user page as a communicative notice about the user or to show things they like. You are free to make your own and add them here. If you cannot, then you can leave a request on the talk page.
Next, create a template (a page in the Template: namespace; see Help:Namespace for more info) with the name of the userbox. Names of userboxes are generally short.
You can now start to make a userbox. Copy the usage code from Template:Userbox and paste it in the new userbox you're making. You can then fill in the fields to create your userbox.
Find or create a userbox you want to add to your page. You can find many precreated userboxes on this page and its subpages or Category:Userboxes.
Copy the code. The code will appear {{name of userbox}} and is usually displayed next to the userbox. If you can't find the code it is the name of the article minus "Template:" between two opening and closing curly braces "{{" "}}"
If you find your userboxes are all over your user page, then feel free to make use of Template:Userboxes and its companion Template:Userboxesend. These templates will sort everything between them into a table, making all your userboxes into a nice, clean list. For example,