You can build web forms that actually submit data to a server using nothing more than pure HTML. You can do this by specifying an action on your form element.
Nest the existing input element inside a form element and assign "https://freecatphotoapp.com/submit-cat-photo" to the action attribute of the form element.
Your code so far
<h2>CatPhotoApp</h2>
<main>
<p>Click here to view more <a href="#">cat photos</a>.</p>
<a href="#"><img src="https://bit.ly/fcc-relaxing-cat" alt="A cute orange cat lying on its back."></a>
<p>Things cats love:</p>
<ul>
<li>cat nip</li>
<li>laser pointers</li>
<li>lasagna</li>
</ul>
<p>Top 3 things cats hate:</p>
<ol>
<li>flea treatment</li>
<li>thunder</li>
<li>other cats</li>
</ol>
<input type="text" placeholder="cat photo URL">
<form action="/url-where-you-want-to-submit-form-data"></form>
</main>
Your browser information:
User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36 Edg/87.0.664.66.
@mry232959 as @jwilkins.oboe said have a look on your html structure. You have two inputs and forms in your code you provided. The one close to the end needs to be changed.