If this is your first PHP/MySQL project then you really need to start with the basics:
1. Learn how to create new tables in MySQL (this is much easier if you have access to phpMyAdmin)
2. Learn how to make a connection from PHP to MySQL
3. Learn how to send queries to MySQL from PHP
4. Learn how to parse the results of your queries
Even if you're good at programming it will still take a while to get up to speed with PHP - I found the syntax very easy to pick up but should have spent a lot more time learning what functions were available. Also, you never really get a feel for how good you are with a language until you start having to solve a complex problem
I think the project you're trying to accomplish is quite ambitious so you probably need to scale down your ambitions initially and then add features as you go along. You also need to look at what the application
must do and
what it would be nice to do - allowing customers to find a particular business would be 'core' whereas tracking take-up/referral rates would be 'nice'.
As a plan of action, you need to:
1. Store business information in your database
2. Define two or three main search criteria that customers will use to find a particular business
3. Create your search form
4. Take the values in your search form and insert them into a query
5. Parse the results in a way that will be useful to customers (IE a list view)
6. Display the full record for each business
7. Create a form that will allow customers to contact the businesses by email
8. Create a script to email the contents of this form to the business and CC: it to the customer at the same time
I hope you'll be able to appreciate that that's quite a lot of work involved for a fairly basic application (let customers search for a business and then let them send an email to it) so I'd suggest you try and accomplish this first and then look at how you can expand it afterwards.
HTH,
M_G