VirtueMart Core Modules have absolutely nothing to do with "Joomla! Module", which are sideblocks in your Joomla! site.
Core Modules build a part of your store and are used to manage the different sections and their access permissions.
Caution
You need to act carefully in this part of VirtueMart. Changing Core Modules and their permissions can result in locking out other users or even yourself from the store.
Core Modules are managed in the module list, which can be accessed through "Admin" ⇒ "List Modules".
To add a new module, click "New" in the top of the list and fill out the fields in the module form.
Don't forget to save and the new module is added to the list.
You can modify existing modules. To do so, just click on the name of a module in that list and a form opens and you can modify the properties of this module. Again don't forget to save your changes.
To remove one or more modules from the list, either click on the "trash bin" icon in the last column of each row and confirm to remove the module or select modules and click on "Remove" in the toolbar.