main.lua

-- main.lua
display.setStatusBar(display.HiddenStatusBar)
local centerX = display.contentWidth / 2
local centerY = display.contentHeight / 2

local sheetInfo =  require("myimagesheet")
local myImageSheet = graphics.newImageSheet("myimagesheet.png", sheetInfo:getSheet())

local background = display.newImageRect(myImageSheet, sheetInfo:getFrameIndex("background"), display.contentWidth, display.contentHeight)
background.x = centerX
background.y = centerY