Note that to add users to your CyberRisk account you need to be an "account admin". Assuming you are an account admin, you should see an Account Settings link within the left nav menu. To add a user, click on this link.
Then, on the account settings page click the Invite User button in the top right corner.
On the invite user screen, enter the email address of the colleague you want to invite to your account. Select any additional permissions you want this user to have. Most users will not have any additional permissions. Click Send Invite to send an email invite to the desired person.
The user should receive an email invite with a link to follow to register for UpGuard CyberRisk and be added to this account. The user should also appear in the Users tab of your Account Settings page.