Mr. lumbago published a good explanation text about D3. Good job! He is the author of online book "XOOPS Cube textbook for non-tech people" (Formal Japanese title may be "XOOPS Cube textbook for people with majors in the school of humanities").
All of his articles are very good! But, if these articles are translated to English, it's difficult to keep the quality because essence of them may be lost.
But, you can read other textbooks, which are XOOPS Cube Legacy Basic Tutorial and XOOPS Cube Legacy Kick Start Guide. They are still poor, but many people improve them.
For example, see the first tutorial. The draft of the tutorial was contributed by me. But, that was bad quality and was written in my poor English. However, the first part of the tutorial had been corrected and improved already. Now, it is good quality.
XOOPS Cube Kick Start Guide is good also, because user has corrected sentences and improved.
However, one happy problem is here. When I contribute English articles, I often keep its Japanese edition, to contribute it for Japanese community. But, because English edition is corrected and improved much better, Japanese edition is not used. ;)