Please help new to this

https://developer.mozilla.org/en-US/docs/Learn/Getting_started_with_the_web/CSS_basics

https://www.w3schools.com/css/css_intro.asp

Spacehey will limit what you can edit from the default profile I recommend right clicking on a part of your profile and clicking inspect element to find the class name of the object your trying to change. It will take time to learn be patient and have a play around.

Another option is just to use a pre made theme/layout I have one on my profile or theres more on the layouts page.

On the HTML front here's a couple more resources

https://developer.mozilla.org/en-US/docs/Learn/Getting_started_with_the_web/HTML_basics

https://www.w3schools.com/html/html_basic.asp

again you can use CSS to style any html you add