How to make it so that you click a button and it responds to the click?

Hello, I am a very new Roblox scripter and I would like to know how to do this. I've learnt basic things like variables, functions, and arithmetic. If you add the GUI button icon what do you do from there?

Hello, I am also a new roblox lua scripter. Here is something you can start off doing if you want to mess with "Guis" that do something when a button is clicked. The lines of code you see below is just some simple lines of code i've learnt in a day or two.

-- Made by Nitrolux200, Instructions below.
-- In "StarterGui" add a "ScreenGui" and name it however you like.
-- Insert an "ImageLabel" inside the "ScreenGui", put the image in the "ImageLabel" and make visible to false. 
-- Insert a "TextButton" and inside the "TextButton" add a "LocalScript" inside.
-- Go in the local script and copy and paste the lines of code below if you want to.

local image = script.Parent.Parent.ImageLabel 
local button = script.Parent
visible = false

script.Parent.MouseButton1Click:Connect(function()
	if visible == false then
		visible = true
		image.Visible = true
		
	else
		visible = false
		image.Visible = false
	end
end)

button.MouseEnter:Connect(function()
	if image.Visible == false then
		button.Text = "Open Image"
		
	else
		button.Text = "Close Image"
	end
end)

button.MouseLeave:Connect(function()
	if image.Visible == true then
		button.Text = "Close Image"
		
	else
		button.Text = "Open Image"
	end
end)

-- Script works just fine, if for some reason it doesn't work contact me "ASAP" !

P.S) if you want to accpet this answer as the "my question answered" since I gave you an example i'd be very appreciated :)