It's not really that easy sher. You usually need to prove that it's worth paying for what you offer. Time and money will be involved in this before you can get some return.
I think paid sites work where you have a certain type of business offline and you offer the paid service to content as a type of customer service.
For example, if you were a lawyer or accountant, your clients would sign up for a monthly fee and support would be provided through the paid section of a forum or website.