Help:Userboxes
Userboxes exist for the purpose of showing things about yourself, such as your gender, age, character preferences, which games you own, amongst many other things.
Displaying a Userbox On Your Page
Use either the {{userbox container l}} or {{userbox container r}} template, depending on whether you want the userboxes displayed on the left or the right. You then add the actual line(s) of userbox code, copied from Help:Userbox List. At the end of the list of userboxes, you should also add {{Userbox container bottom}}.
For a list of userboxes, see Help:Userbox List.
Creating a Userbox
When creating a new userbox, you don't need to worry about div classes and other HTML code you may see in other boxes. All the code you'll need is contained in Template:Userbox, and you can use its parameters to add customised text, images and colour, although you can still start from scratch if you want. A simple userbox is constructed using the following format:
{{userbox |id= |id-background= |info= |text-background= }}
For the two "...background" options, specify a colour either by name, hex code or using Template:Color. The "id" field can be either text or an image, displayed on the left. The "info" field is the text displayed on the right.
Once created, simply add your resulting code to the Userbox List, and if desired to your userpage.