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Go to the left had menu, select Contacts
Click the Add button on the left hand side
Fill in the relevant fields for the person you are adding. The Contact Details and Personal Details sections are the most relevant
Go to the Requirements section and tick the Internal Staff box
Click the Save & Close button
Go the left hand menu, select Users > Manage and use the top search bar to find the relevant users (or just click the search button to view all users)
Double click the user from the list that you have just added, or right click and select Edit
Go to the Associated Contact field. Start typing the name of the contact you've just added and select the appropriate person from the drop down list
Click Save
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