If you are talking about the Macros that are ran from the Datacad Toolbox or Macros menu at the top of the screen, you can look at https://www.datacad.com/ddn/tutorial/dcal_tut.html as a place to start.
That tutorial is quite old, but is still good for 'Classic' DCAL.
There are newer versions of DCAL available (DCAL for Delphi - often abbreviated as 'D4D', and DCAL for C++). Joe Sosnowski wrote a series of D4D primers which are available on the DDN forum (first primer is at
https://www.datacad.com/bbs/viewtopic.php?f=14&t=16066). I haven't actually read Joe's primers, but assume they would be helpful - I think Joe wrote them while convalescing after a motor bike accident, but he hasn't been active on the forum since his full recovery.
The newer versions of DCAL have both advantages and disadvantages over the classic version. You will find some of my thoughts on this at
https://dhsoftware.com.au/dcalcompare.htm.
The DDN forum would be a good place to look for DCAL information or to ask questions about it. A number of sample macro source codes are supplied with DataCAD, and more are available on the
DDN Open Source Exchange page. The source code for most of my own macros is available on
bitbucket with some notes about them at
https://dhsoftware.com.au/source.htm.
Regards,
David H