Thomas Klein gives with his series of articles "DrDialog, or: How I learned to stop worrying and love REXX" a good introduction in using DrDialog, a development environment for REXX programs with a graphical user interface. Episode 1 is published in VOICE September 2002. Volume 14 is published in June 2005.
Although VOICE is very accessible, it is quite challenging to find all articles about DrDialog. Episode 3 is also not everywhere to download. I have downloaded all the English HTML episodes and brought them together in one file with an index from which each episode can be started.
Furthermore all episodes have choices between forward and back to the next or previous episode. With DrDialog index you can go back to the menu. All articles are in one directory.
Below you can download the VOICE article series "DrDialog, or: How I learned to stop worrying and love REXX" by Thomas Klein.