Looking for a SIMPLE tutorial to make a 'window'

[Aglaea]

I am looking for a simple tutorial that shows me how to make a simple window with a background in a colour of choice, some lines of text and that is movable. May be in Lua or FrameXML, but please motivate your choice. So far, tutorials and code examples I see are just overdone and give much more than this. For me this makes it confusing to get this done.