Perhaps also use this source as a template for starting your own page, as follows. Now work up from the bottom, skipping the last line. You now have a valid HTML document, though not very meaningful as to content. Spaces before or after them do not affect the meaning of HTML tags - but can represent the existence of space for the above formatting rule. A few tags are unpaired.
Most tags are paired - a slash is required in the second tag of a pair.
Here one or more attribute specifications may be optional or required, separated by spaces. Often there is need for a list. Topic discussed is escape sequences required when you want these characters displayed, and don't want formatters to see them as parts of tags, etc. Sometimes you want to include a character that you expect browsers to be able to display, but that is not on your keyboard. This list item, broken into two paragraphs, hints at the complexity permitted in a list item - including making them several levels deep.