How do i do 9. Self Closing tag in: Introduction to HTML

I have been stuck on it for some time

Have you read the lesson text that describes what a self-closing tag is?

Briefly, it is any tag that does not have an ENDTAG, only and OPENTAG, and can thus not contain anything.

<p>This is a container element with opentag and endtag.</p>
 ^                                                      ^
OPENTAG                                              ENDTAG

Example list of self-closing tags

<hr>    or    <hr/>    or     <hr />

There are others but i think you get the idea. Re-read the lesson and be sure you understand and follow the instructions.