ServiceNow Service Portal modal windows

Very new to Service Portal and modal windows. I'm creating a portal page and want to include modal windows for a couple different things. First, I want a modal welcome note to appear when a user lands on it for the first time. I've already created the welcome note in an HTML widget, but am confused how that would interact with the modal widget that comes with Service now Service portal. scondly, I've created some links (also using HTML widget) that would take a user to a knowledge article and would like to utilize modal windows as well. After playing around with the modal widget, I'm confused what to enter in each of these boxes in order for it to work correctly:

Also is this meant to work with other widgets in Service Portal or is it easier to create a new widget and just code the modal part of it from scratch?