GMM:

It all depends on why they pick the wrong workbook. If all the macro will do
is limit the number of selections or make the selection names clearer, you
could probably do that by renaming the workbooks and grouping them in separte
categories in different files or folders.

Bear

In Excel and Word you can record a macro while doing the operations you
require. Open Excel with a blank workbook. Record a macro with menu
Tools/Macro/Record New Macro...  A dialog will show asking if the suggested
name of the macro module is OK. Note the name and click OK. A record toolbar
will popup. It will already be in record mode. Open the workbook you want.
After it is loaded, click on the stop button in the record toolbar. Press
ALT/F11 key combination to bring up the VBA editor. In the Project window,
expand the module folder, double click on the module number you just
recorded.
Look at the code and alter, if needed. Macros can be assign to hotkey
combinations, menus, and toolbar buttons.
May this will get you started and know what question to ask next.