Forum:Making user subpages

This might be a question with an obvious answer but I'm not sure how to create an user subpage like this one. How can one be created? I want to put my own Smash Ultimate CSS on it using stock icons like

Gligar2007 (talk) 00:48, April 23, 2021 (EDT)
 * User:Gligar2007/(title of subpage). DF used the DISPLAYTITLE template to omit the stuff before the slash. Cookies CnC Signature.png Creme  01:01, April 23, 2021 (EDT)