Using pentax Auto Extesnion Tubes

Just won an ebay and received this K Set of tubes. I'm unfamiliar with macro/closeup photography, and initial use of these is surprising.
With my 300mm and all three tubes, I get up really close. Standing 6m away from my orange trees, I get so close you can see all the grain of the orange skin. Cool, can't wait to see the prints.
With a 50mm, the defintion of garden flowers is superb but you have to get too close with all three tubes. need to learn a dela here.

Any hints from fellow explorers with these would be great. The guy I bought them from was really helpful, and suggested buying the book
"John Shaw's Closeups in Nature". haven't foudn it yet

Unfortunatly the manual that came with them has many pages so stuck together that they rip. Its a shame since the back pages have tables with information on focal lengths per lens type. After much searching, I came across craigcamera see http://www.craigcamera.com/ib_pentax.htm
pretty useful for all sorts of rubbish, they're charging 415 a piece for these manuals, if anyone has a better idea ...

Thx

try this article on ePHOTOzine it should help you: http://www.ephotozine.com/techniques/viewtechnique.cfm?recid=134