How to create a blank xml file?

How do I create a blank xml file on a mac? text editor?- what program on a mac would I use to do that? Sorry - I am a tech noob - my webguy went home for the day. Trying to teach myself a bit - I am supposed to save as "all files" but I don't see hwo to do that...any help would be appreciated!

On the command line using the below should work:

or


If you want to make it using an edtior, save as, all files and manually type the extension on the file name should work too, you can also set TextEdit for plain text on the preferences.