Paste the code on your website
Simplest: in your website editor open the page, add an HTML block and paste both lines into it together. Save and publish. The form takes the width of the block you put it in. The names of the right blocks in popular systems are below.
Better for statistics: paste the first line (the script) once in the head of the whole site, in the place your system calls "head code", and leave only the element on the page with the form. A script present on every page remembers where the customer entered your site from, so the panel shows that a lead came from an ad or a search even when the customer reached the form from the third page. Without the element the script draws nothing and sends nothing.
HTML · head of the whole site
<script type="module" src="https://offerandum.com/widget.js"></script>
HTML · the page with the form
<offerandum-form form-id="f_YOUR_FORM"></offerandum-form>
The order does not matter, and nothing breaks if the script ends up on the page twice: the element works either way.