If you cannot see the Express menu in the Acad2000 menu bar, most probably you still have the directory: \Acad2000\Express\ If so, then you do have the Express menu file but it is not visible on the menu bar. You need to load it.
Here is how to load menus from Acad2000 menu: TOOLS> CUSTOMIZE MENUS > BROWSE > \Acad2000\Express\Acetmain.mns LOAD Then you see it in the menu bar.
If you do not have the said directory, then as experts have commented correctly above, you have to get the directory first. Then you load the menu.
In Acad14 this (Express) was called Bonus and was small enough to send per e-mail attachment.
Wait - Acad2000\Express\ is not that big: zipped, 560 kB. Unzipped, 1.94 mB.