Within Teamwork Projects, you can create external companies to add your users to.
To do this, select the 'People' section to the top of your projects site, and select the 'Companies' tab:
Adding a company
To create a new company on your site, click the 'Add Company' button in the top right of the companies area:
You will then be able to add the details for the new company, including any address details in the 'Address' tab.
You can add public notes about the company in the 'Profile' tab, and private notes in the 'Notes' tab (they will only be visible to people in the owner company).
Editing a company
You can click the name of any existing companies in the list to view the company details page.
To the top right, you will see an 'Edit this Company' button:
Choosing the 'Edit this Company' button will provide the same options as above.
For more information, see: Adding or updating a user's company