Hey,
to add modules to "My Modules" click on the suitcase icon of the module in the module finder.
To remove modules click again on the suitcase icon.

To add all modules of a rack to "My Modules" go to the rack view page.
Top left subnavigation you find an entry Edit->Add all to My Modules.

Beep, Bopp, Bleep: info@modulargrid.net