Manage your users in the Permissions tab. Here you can add and remove users to your account and maps.
Click on a user to see which maps they are allowed to access. To add them to a map, check the boxes to the left of the maps and click Save at the top right. They will receive an email inviting them to the map(s).
Click on the Add User button at the top right of the page. Enter their email address and click Add. The user will receive an invite email only when they have been added to a map.
From here you can change User permission levels for each map. Users can be set to Read-Only or Edit. These edits will automatically be saved to the original dataset and cannot be reversed. In addition to altering the permission levels per map, you can also add an expiration date to their access of each map you've shared with them by clicking the line next to the map in the Expiration column and selecting a date on the pop up calendar.