How do I 'tile' an image & save the pattern?

As well as creating images, I would like to use them 'tiled' to produce a background, e.g. Polkadots / Gingham etc. I have worked thru all of the tutorials which I found very informative, however, I didn't come across any instructions referring to tiling an object or creating &/or saving a pattern.

Any advice would be gratefully appreciated!

Cheers!

Nat