Affiliate Users can be added under Admin>Users
When you create the user, you will need to select the affiliate access level type. Upon doing so, you will also need to choose an affiliate profile to tie this user to.
Once this is done, the affiliate will be able to log in and only see stats that relate to their affiliate profile.
Note: A username can only be used once throughout all of Konnektive's databases. If the username you are trying to use is already taken, you will need to make it unique in some fashion.