This article illustrates how to create a client portal user.
Go to a Contact
Click the Work With Portal
Select Enable Customer Portal User
Complete the New User Form
All fields will normally be set to the best selection for default values.
Edit as necessary.
Make sure you set the Profile field as shown in this screen shot
Click Save.
An email will be sent to the contact with log in and other information based on the Email Templates configured for the Client Portal
Verify How the Portal Looks to a Client
Go back to the Contact.
From the Work With Portal button
Select Login As Portal User as shown in the screen shot here