Help - how to use tag manager

Hello community,
i would like to use the matomo Tag Manager and need help for this as i have never done it before. I would like to place ads on LinkedIn and redirect them to our landing page and would like to track the conversion with matomo. I have created a container and entered the LinkedIn Insight tag with my partner ID. What do I have to do now with the trigger, what do I have to select when I want to see how many user come to the site and how many click on the “Free Demo” button. And what do I have to select in the variables and in the versions?

Please help me, we are currently switching from google anayltics/taqg manager to matomo.

With best regards