After you have created your account, go to your user page by clicking on your username in the bar of links at the top right of the page.
When you arrive at your user page, it should open in VisualEditor by default because it has not been created yet. If it does not, click the "Edit" tab in the right-hand tab grouping.
Once VisualEditor is working, you will be able to write text on your user page, just like in a word processor.
You can add bold text by clicking on the "style text" dropdown menu in the editing toolbar.
You can add italic text by clicking on the "style text" dropdown menu in the editing toolbar.
You can add links to Wikipedia articles by clicking on the "link" button in the editing toolbar.
After clicking the button, start typing to search for Wikipedia articles and select one to link.