Implementing UI?

I am making a multiplayer fps game in Unreal Engine 5 and I have all of the UI buttons and pages ready to go, but I am not super familiar with creating UI. I have created some basic UI for my players screen like ammo and health. I can create the UI and put in the pages and buttons that’s the easy part, so I need help making them do things, for example connecting the different game modes to the buttons. I tried searching it in google but most of them don’t go in depth and only show how to make a basic menu with play and quit button. My menu is going to be more complicated than that, I want a game mode selection, armory, settings, etc. If anyone knows of a tutorial, course, or video that will go a little more in depth for what I need that would be great!