Roblox Example GUI ep1

local GUI = Instance.new("ScreenGui", game.CoreGui)
GUI.Name = "My GUI"
-- Frame
local mainFrame = Instance.new("Frame", GUI)
mainFrame.Size = UDim2.new(0, 100, 0, 100)
mainFrame.Position = UDim2.new(0, 300, 0, 50)
mainFrame.BackgroundColor3 = Color3.new(1, 1, 1)
mainFrame.Name = "My Frame"
mainFrame.Active = true
mainFrame.Draggable = true
-- Title
local title = Instance.new("TextLabel", mainFrame)
title.Name = "My title"
title.Text = "This is My GUI"
title.Size = UDim2.new(0, 100, 0, 20)
title.BackgroundColor3 = Color3.new(1, 1, 1)
title.TextScaled = true
title.Position = UDim2.new(0, 0, 0, 0)
-- button
local button = Instance.new("TextButton", mainFrame)
button.Size = UDim2.new(0, 100, 0, 20)
button.Position = UDim2.new(0, 0, 0, 20)
button.Name = "My Button"
button.Text = "Click me"
button.TextScaled = true
button.BackgroundColor3 = Color3.new(1, 1, 1)
-- Event when clicked
button.MouseButton1Click:Connect(function()
    print("hello world")
end)

-- Open / Close Button
local Close = Instance.new("TextButton", GUI)
Close.Size = UDim2.new(0, 40, 0, 40)
Close.Position = UDim2.new(0, 0, 0, 150)
Close.Name = "Close and Open"
Close.BackgroundColor3 = Color3.new(1, 1, 1)
Close.Text = "Open/Close"
Close.TextScaled = true
-- Event Open and close
Close.MouseButton1Click:Connect(function()
    if mainFrame.Visible then
        mainFrame.Visible = false
    elseif not mainFrame.Visible then
        mainFrame.Visible = true
    end
end)