I need help making the gui background rainbow for basic admin essentials anyone know what to do?

--]]

    ['Super Admins'] = {

    },

    ['Admins'] = {

    },

    ['Mods'] = {

    },

    ['Banned'] = {

    },

    ['Group Configuration'] = {
        {
            ['Group ID'] = 0,
            ['Group Rank'] = 0,
            ['Tolerance Type'] = '>=',
            ['Admin Level'] = 0,
        },
    },

    ['Command Configuration'] = {
        ['fly'] = {
            ['Permission'] = 1,
        },
        ['unfly'] = {
            ['Permission'] = 1,
        },
    },

    ['Prefix'] = (':'), -- The prefix to the admin, i.e :cmds or :sm hi
    ['Kick Reason'] = ('You have been kicked from the server.'), -- Displayed to people that are kicked.
    ['Ban Reason'] = ('You have been banned from the game.'), -- Displayed to people that are banned.
    ['Shutdown Reason'] = ('This server is shutting down..\nTry joining a different server!'), -- Displayed to people when the server is shut down.
    ['Server Message'] = ('Server Message'), -- Displayed in the :sm command's title.
    ['Server Lock Reason'] = ('The server is locked.'), -- Displayed to people being kicked that try to enter a locked server.
    ['Trello'] = false, -- Use trello? HttpService must be enabled.
    ['Trello Board'] = (''), -- Trello board ID.
    ['Trello App Key'] = (''), -- Private trello application key.
    ['Trello Token'] = (''), -- Private trello token.
    ['Creator Debugging'] = true, -- Allows the creator to debug potential issues with the admin.
    ['Donor Perks'] = true, -- Gives people who purchase an admin donation the ability to cape, put hats on, etc.
    ['Public Commands'] = true, -- Will people that are not admin be able to say :cmds, or !clean?
    ['Auto Clean'] = true, -- Will hats and gear automatically be cleaned up every so often?
    ['System Color'] = Color3.new(0/255, 1, 1), -- Color of the admin's guis.
    ['Tools Location'] = game.ServerStorage, -- Where the :tools and :give command will get tools from.
    ['Command Confirmation'] = false, -- Validates certain commands like :Ban all, or :PBan all.
    ['Datastore Key'] = ('BAE_#$DGF') -- What cape data, ban data, etc. is stored under. Changing will wipe it.
}

That is the most relevant part of the script Please help!