Thats it for the Photoshop portion, next hit the 'Edit in ImageReady' button located on the Toolbar.
Once in ImageReady, select the Output menu option (encircled in Red) and from the list choose the 'Other' feature, as I have captured below.
Once in the Output dialog, hit the 'Next' command until you reach the Background settings.
Tick the View Document as 'Background', then OK to commit the Output settings.
Finally, go 'File/Save Optimized As' as captured below.
Set the following options as captured.
Unique filename.
Save Type both .html & Images.
Choose the 'Custom' settings created earlier.
View the final output of this tutorial
here.
Here is a smaller version of the tiled background.
Plenty of room for possibilities here.
Click the below thumbnails for variations.