How to add a Flickr API to my current HTML Site – Warning: Beginner

I was currently working on a project for my html, css and javascript web developing class but I have a hit a road block on the very last unit. they provided a bunch of resources to teach you api but most tutorials do not even work… so i selected one of the provided api resources they recommended for use, which was flickr. I selected a testimonial api from flickr but im not sure on how to integrate it as there is little to no direction when yiutubing it or googling it and im currently at my wits end myself as im very burnt out!

I was wondering if anyone can provide a solution or some resources to help me out?

here is the flickr website and code: https://www.flickr.com/services/api/flickr.testimonials.addTestimonial.html


`<rsp stat="ok">
  <testimonial id="72157659275062162" date_create="1491516194" date_approved="0" approved="0" body="great contractor!">
    <by_user nsid="45937598@N01" path_alias="" username="TQ" ispro="1" is_ad_free="0" realname="Tariq Q" 
/>
    <about_user nsid="516314214@N05" path_alias="sidasad" username="Sad" ispro="0" is_ad_free="0" realname="Asad Siddique" />
  </testimonial>
</rsp> `

Also here is my current index page where i want to integrate the code.. i was following a tutorial which i very late realized had nothing to do with API inetgration so ive added the code from flickr into a div container as of current.

`<!DOCTYPE html>
<html>
<head>
    <title> MH Construction Concrete Cutting & Coring Ltd.</title>
    <link rel="stylesheet" href="stylesheet.css">
  <link rel="stylesheet" href="https://code.jquery.com/ui/1.13.3/themes/smoothness/jquery-ui.css">
  <script src="https://code.jquery.com/jquery-3.7.1.js"></script>
  <script src="https://code.jquery.com/ui/1.13.3/jquery-ui.js"></script>
    <script src="script.js"></script>
   
        <h1>MH Construction Concrete Cutting & Coring Ltd.</h1>
        <h3><center>Are you looking to enhance your property with precision concrete cutting and coring services? Look no further than MH Construction Concrete Cutting & Coring Ltd!</h3></center>
        <meta charset="utf-8">
</head>
<body>

<div id="tabs">
  <ul>
    <li><a href="#fragment-1"><span>About Us</span></a></li>
    <li><a href="#fragment-2"><span>Our Projects</span></a></li>
    <li><a href="#fragment-3"><span>Our Services</span></a></li>
    <li><a href="#fragment-4"><span>Bookings</span></a></li>
  </ul>
  <div id="fragment-1">
  <h2>About Us</h2>
    <p>MH Construction Concrete Cutting & Coring Ltd. is committed to providing top-quality services with a focus on safety and customer satisfaction. Our team of experts is equipped with the latest tools and technology to ensure precise and efficient results.</p>
        <p><a href="socials.htm">Click Here To Our View Socials Page</a></p>

<div id="testimonialsContainer">
  <h2>Testimonials</h2>
  <ul id="testimonialsList"></ul>
</div>
<rsp stat="ok">
  <testimonial id="72157659275062162" date_create="1491516194" date_approved="0" approved="0" body="great contractor!">
    <by_user nsid="45937598@N01" path_alias="" username="TQ" ispro="1" is_ad_free="0" realname="Tariq Q" />
    <about_user nsid="516314214@N05" path_alias="sidasad" username="Sad" ispro="0" is_ad_free="0" realname="Asad Siddique" />
  </testimonial>
</rsp>
  </div>
  <div id="fragment-2">
     <h2>Our Projects</h2>
       <p>Explore our previous projects to see the quality of our work and get inspired for your next renovation or construction project.</p>
       <p><a href="projects.htm">Click Here To View Our Projects Page</a></p>
  </div>
  <div id="fragment-3">
   <h2>Services</h2>
<p><a href="Our Services.htm">Click Here To Visit Our Services Page</a></p>
     <p>In any of our requested services we abide by Alberta Government Health and Safety Regulations. Please see the attached Alberta Government Safety Website for more.</p>
       <p><a href="https://www.alberta.ca/obligations-work-site-parties">Government of Alberta Safety Website Disclosure</a></p>
  </div>
    <div id="fragment-4">
   <h2>Services</h2>
<p>Ready to book an appointment? Please see our email booking form below and suggest some times and dates you are available and we will get back to you shortly within 4-5 business days. Feel free to use our viewable calendar below to aid in choosing your next appointment date! </p>
       <p><a href="book now.htm">Click Here To Book Now</a></p>
</div>
 
<script>
$( "#tabs" ).tabs();
</script>

</body>
</html>

    <p>Author: Keisha Shah</p>
    <p>Last modified: <span class="date">August 16th, 2024</span></p>`

ive tried the following: So I made a div id section with testimonials following him, and integrated the code to see if it would work. On the index page of my site, only problem was using the code it was not showing up so I used the above source and a variety of other sources to see if I could make it work – I tried using chrome inspect only error detected was : Uncaught Type Error: Cannot set properties of null (setting ‘inner HTML’)

at generate Calendar (script.js:44:24) 

at script.js:50:1