EPiServer has a code sample regarding this:
Use EPiServerProfile for the same purpose you used PersonalizedData before. What values can be stored (what keys are valid) in the profile have to be specified in the profile section of web.config. If you installed using the deployment center you will find some predifined properties like Company and ZipCode in this section, you can then add your own. However, none of these properties will show up in the edit/admin user administration unless you develop plugins for them (targeting PluginArea.SidSettingsArea).