Strangely enough, this isn't in the readme. I can't even tell you to RTFM.
Anyway - Unless you changed MacroQuest.ini, macros should go in the Macros subdirectory of wherever you put the Release dir/compiled binaries dir.
You start them by typing "/macro thisismymacro" and end them by "/endmacro" on one of your chat windows in EQ. Macro parameters are done on the commandline if you're using Params. So, "/macro thisismymacro param0 param1" etc..
FWIW.