Small-Print Tutorial - the Word
Once you've created an image you'll often want to add some kind of text to it.
Just click on the Text Tool icon in the Toolbox (or Shift+T or <Tools><Text>), drag in your image to create a rectangular selection of the appropriate size, and type your text.
By default, the text will be in the current foreground color. Just click on the Color rectangle in the Text Tool Options window to change. (You can change the Font and size here too.)
I usually click the third of the Justify icons to make sure the text is centered.
Most of the cheeseburger/meme/motivational/crap images you see will use the "Impact Condensed" font, in white, with a black border.
To get the border, set the foreground color to black, make sure your text layer is selected, click <Layer><Text to Path> and then <Edit><Stroke Path> with Line Width 2.
(Note this converts the text layer to a picture - so you can't easily fix typos afterwards.)
For more fun, you can mess about with the pre-set scripts under <Filters><Alpha to Logo> or <File><Create><Logos>.
That's how I generated these.