Making a Package is relatively easy. To summarize what you have seen already in the other answers:
Wrap your procedures in a module()...end module; construct:
description "What it is for";
export ...; # the procs of variables you want to access
local ...; # local variables
option package;# this makes it a package
All of the above is within one execution group.
You then need to save it as a .mla library, I do it like this:
where I have pre-pended my own library directory to the libname list in my .mapleinit file.
I keep the Maple workbook separate so whenever I need to update one of my libraries I just open the worksheet; make the changes and execute the thing which saves it where I want it.
Occasionally you need to compress your library to clean out older versions. I have forgotten how to do that but help on LibraryTools will tell you.