Start on the User Accounts Tab
Click on Create new User Account
Fill in the appropriate contact information and select the company you want this contact to be added to
Go back to the top of the new user account area and drop the box at the top left to click login. Once in login, put the email you have added for this account, check the 'Enabled' box, and then create and detail
Once you've hit create and detail, it will then open up the detail editor where you can enter the specific contact and company details
Save and Exit and you've created the account. They can now be invited to a campaign
Now invite the employee via their specific employee email you added