I want to set this button to shoot when pressed. I am a beginner. Please help me

This is a very vague question. But I think what you need to do generally speaking is get a reference to wherever you are spawning your “projectiles” or bullets or whatever is being “shot” and when you press that button, you are going to want to have a custom event or function in the firing BP that is going to get called from the widget by using the “On Clicked” event for the button. So like this:

In widget BP:

  1. On Clicked → Get Reference To Character/Firing BP
  2. Call function/event to fire projectile

In Character/Firing BP

  1. Create custom event/function that spawns a projectile (Spawn Actor From Class Node)

If you are just starting out these tutorials may be helpful to you: