You'll have to add fields in UserProfile table and then you'll have to generate your DAL entities. We have exposed MonoX DAL source code to enable all users to easily extend it. Although you will have to obtain a license for the LLBLGen Pro Designer in order to generate a custom DAL, it will enable you to open a DAL project, add new entities for tables that you've created in the database and generate a new DAL in just a few clicks. After this process is finished, you will have the access to your newly created entities across the MonoX project.
MonoX DAL is upgraded to LLBLGen version 4.1. The latest package is available on GitHub
Then if you'd like to search on these new fields, you'll have to update or override a method in UserRepository:
useFullTextIndex, Guid applicationId,
Hope this can help you.