The Stroke way:

Write the text with Text tool and fill it with desired color.
Change the foreground color to black (or any other color that you want on your outline)

Go to the Edit menu and select STROKE and set the width to 2 pixels

The Expand selection way:

This way may seems a little bit more complicated than the "Stroke way"  but the main advantage is that you can chose to  have multicolor in the outline

Start with a new image in RGB mode.
Write the text and Save the selection.

Go to SELECT/MODIFY/ and chose Expand 3 pixels

Add a new layer and fill the selection with desired color

Load the selection that you saved in step 1 and fill it with desired color