Two options:
- Learn the language it was written in (I presume, considering the forum, php) and do it yourself
- Get somebody else to do it for you.
I do not think you will find somebody to write it for you here, based on your current post.
In a more concrete sense:
- Create a user-account & login system to keep trak of the status of people
- Ask people to lgin and/or create an account upon entry
- Based on their status in the database, load paid or free sections.
