I need a business analyst to document and write up requirements for a new website

I need a business analyst to document and write up requirements for phase one of a new website.

I have wireframes and I can explain the site but I need requirements written up professionally so that they can be sent to a offshore development company for a quote and build.

You must have experience in writing business requirements and be able to show me examples of your work.

You must be familiar with social websites with registration, profiles, forums and Facebook integration and preferably have written requirements for a social website before.