Hi, I'm Soupperson1 and this is a step by step guide on how to create a userpage.
Click your username in the top right corner.
A drop box should appear
Click the redlink that has your name.
This page should come up. Press the orangish yellowish button saying "Use wiki userpage", it's in the top right corner.
Click the blue link that says "edit this page", as highlighted.
This page should come up.
Begin to write your user page, take your time and don't rush. It can be as long or as short as you want.
I suggest adding user boxes from Brickipedia:Userboxes
Once it's read over, you can press the "Save page" button, it's the grey button in the bottom left corner.