Set core GUI Roblox

-- Creating a ScreenGui (top-level GUI object)
local screenGui ="ScreenGui")
screenGui.Parent = game.Players.LocalPlayer:WaitForChild("PlayerGui")

-- Creating a Frame GUI object
local frame ="Frame")
frame.Size =, 0, 0.5, 0) -- Setting size relative to the screen
frame.Position =, 0, 0.25, 0) -- Setting position relative to the screen
frame.BackgroundColor3 =, 0, 0) -- Setting background color to red
frame.Parent = screenGui -- Setting the parent of the frame to the ScreenGui

-- Creating a TextLabel GUI object as a child of the Frame
local textLabel ="TextLabel")
textLabel.Size =, 0, 1, 0) -- Setting size to fill the Frame
textLabel.Text = "Hello, Roblox Lua!" -- Setting the text content
textLabel.TextColor3 =, 1, 1) -- Setting text color to white
textLabel.Parent = frame -- Setting the parent of the TextLabel to the Frame

This Lua script creates a simple GUI in Roblox using the core GUI system. It starts by creating a ScreenGui as the top-level GUI object and then adds a Frame as a child of the ScreenGui. Inside the Frame, a TextLabel is created to display the text "Hello, Roblox Lua!" The script sets properties such as size, position, background color, and text color for these GUI elements.