I am glad to hear that.
Realize that a fundamental concept of HTML/XML is the format (or syntax) of the entities. You will begin to see this consistently but;
All HTML elements MUST BE contained within angle-brackets. They are intended to confine and delineate the element.
Inside that element there can be numerous attributes. Every element SHOULD contain a matching OPEN and CLOSE tag.
Some content here, which could be more HTML tags
Finally, some tags which do not contain data are not required to have a matching CLOSING tag. However, they ARE REQUIRED to comply with a modified format. The most familiar example is the HTML 'image' tag:
Some content here
Note the way this is self-closing
<img src="the_source_is_metadata" style="style_modifiers_is_metadat" />
<hr /> This is another example
<br /> And so is this
These are the "formal" requirements. However, many browsers will properly interpret (and interpolate) poorly structured HTML. In the world of XML there is much less tolerance, though.
I hope I have not bored you with TOO MUCH DETAIL.