We're not able to provide assistance with HTML customizations beyond this documentation. But there are many excellent, free resources for learning basic HTML that can do a great job teaching you the basics. We've linked to W3Schools' excellent tutorials below. Be sure to make use of their Try It Yourself feature for each topic.
Formatting your text (e.g. bold, italics, underling)
Creating links (like that one!)
HTML attributes (for details like alignment, fonts, font colors, font sizes, and image sizes)