Adding an 'On-Trial' overlay (Dawn Theme)

Store Design
1

Theme: Dawn
Hey folks!
My name is Mike, I run an online resale store with my wife Ashleigh, and because of this, we offer a trial period on our products. so when someone ‘purchases’ a saddle it gets shipped to them and we start a 3 day timer for them to trial the product.

I want to create a system that will allow potential buyers to see when a saddle is currently on trial, since it’s not a guaranteed sale, I’d like to show folks the product but just ‘announce’ that it’s out on trial. (I understand this isn’t massively necessary, I just want to do it)

Please don’t judge but I have a very basic knowledge of programming and I’m using ChatGPT to help me.

Firstly I’ve made a product-trial.liquid and in there contains

{% assign is_trial = false %}
{% for tag in product.tags %}
  {% if tag == 'trial' %}
    {% assign is_trial = true %}
  {% endif %}
{% endfor %}

(I’ve also made a tag ‘trial’)

Now this is where I get stuck as this is what it has suggested next.

Add an overlay to the product image. In the same template file, find the code that displays the product image and wrap it with a div that has a class "product-image-wrapper". Then, add the following code after the div:

The end goal is I’m wanting people to see the stock we have on trial in case the sale doesn’t go through they can add it to the basket and will be notified if it comes back into stock?? Am I going a really long way in doing this?
I’m digressing here…

My question -
where is the product template liquid file in the Dawn theme?

Thanks in advance!