How do you import a bmp to use as a back ground

OK… they do act like a container… but… when you add a text block to it… the button stretches the entire length of the vertical box. When I drag the button out of the vertical box… the button is just the size of the word with little dots around it to resize it…
I will rewatch the video and see if I can puzzle out how to make the button small like it is when it is outside the vertical box