Hi There
I understand you need a php coder to set up a page to access the whatsapp api, i.e. a page to log on, send and receive messages.
I have been coding in php for years now, including writing a full blown blogging and chat website in php and html5 which can be seen at kimnatalie.com.
My 17 year old daughter is a whatsapp user (and a whatsapp expert) so she will be perfect to help me set up and test a system that is easy to use for teenagers.
As the whatsapp api is well documented I do not see this taking more than a couple of days to do the initial setup, with another 2 to 3 days to make sure my daughter is happy with it, ie making usre is matches the functionality of her cell phone.
Please consider me for this project, as I have been programming for over 25 years in many different languages.