New User trying to use a UI button to interact with objective markers

I'm a completely new user to Unity to the point where I don't even know where to look to learn how to do what I'm trying to do. Any direction or assistance is appreciated.

What I have so far: I am trying to make a top down game designed for use on a mobile device. I have a UI and menu system implemented. I have the map with collisions and a player sprite who is connected to the joystick I put on screen.

What I am trying to do is create prefab objective points on the map that appear in random places and have the player use the interact button I put next to the joystick to activate and complete the objective. Ideally a situation where they hold it down until completed but I'll settle for a press the button and be done scenario.

My issue is that I'm not even entirely sure how to approach the issue. Do I need to make a script for the player sprite that makes pressing the button activate an 'interact' state? Do I make it so the button does somet$$anonymous$$ng but only if pressed w$$anonymous$$le in the objective area? I'm not sure where to look to figure out how to do these t$$anonymous$$ngs, any help is greatly appreciated.