Plugin GUI help? [UNANSWERED]

I have this code as well as a GUI inside the plugin, how do I set it so the person using the plugin can see the ScreenGUI?

local hasLoaded = plugin:GetSetting("pluginHasLoaded")
if not hasLoaded then
    print("Welcome to Basic Object Changer! To use, just click on the thing you want to change then click the button that you want to change it to!")
    plugin:SetSetting("pluginHasLoaded", true)
end

local toolbar = plugin:CreateToolbar("Basic Object Changer")

local button = toolbar:CreateButton(
    "Basic Object Changer",
    "Click to use",
    "http://www.roblox.com/asset/?id=145723965"
)

button.Click:connect(function()
    plugin:Activate(true)
    print("Plugin Activated!")
end)

I apologize in advance for the trouble I make.