How to create other pages for links to go to

When I create menus, I do not know what to put in my links html to go to other pages.
For example, if the pages are webdesigners, graphic designers.
then what do I put in the link in the text editor. I do not know what to name my pages. Must they all be named with an .html ext or just for example save the file as webdesigners without an extension.

<body>
<div class="topnav-right"> 
<ul>
<li><a href="webdesigners">webdesigners</a></li>
<li><a href="#">webdevelopers</a></li>

</ul>
</div>

If you’re linking to another page, chances are that the extension will be .html

Say your website is my-website.com

The main page will be located at index.html

Other pages, namely webdesigners and webdevelopers, would be accessible at:

my-website.com/webdesigners.html
my-website.com/webdevelopers.html

As the first user to respond stated, they will end in HTML. EDIT: Unless it is your CSS stylesheet, JS, or similar.

I’d like to add that it can vary depending on how you are setting up your site.

For example, say you’re making a website with Atom or VS Code. You have your main file, the index.html, and say another file in the same folder.

In that case, the url would look like
"webdesigners.html"
In this example, it’d show in the browser as website.com/webdesigners.html

Or similarly, if the page were in a different folder, it’d look something like this:
"folder-name/webdesigners.html"
In this second example, the browser would show it as website.com/folder/webdesigners.html

Sorry if my explanation was poor!

Oh, one other thing! Folders with a space between words will need a dash or underscore between the words, rather than an empty space.
If for example you had “this folder/page.html” the page would not be able to be accessed.
Instead, it’d need to be “this-folder/page.html”