Build a Website

aI want to create a website on a PHP front end and a MySQL backend. The site will have three logins for Admin, Companies Advertising, Users Collecting Commission. Concept: Companies advertise a commission structure based on there business model. Eg: Company (A) Babinda Electrical might be advertising that they will pay $40.00 per $500 in referrals. The company pays the user direct. Companies that advertise take ownership to different areas which are selected based on post code. Eg. Babinda Electrical $40.00 per $500.00 in referral for Electrical work performed in these areas. The company and the users interaction is kept under the users account and the company they are referring to. The company is given access to Gmail, Yahoo upload Commad delimited file so that the company that's advertising can send this to the people and customers they wish to. Users: Will create an account, and if they wish make a referral they do a search for the area and the market they wish to refer. Eg: Accountant in Brisbane area. Between the user and the company they are sending the referral to there is a system that tracks the progress. Eg. User Sent Referral: / Referral received acknowledged. Payment Received: / Payment Sent. Admin: Has a login that can see both sides and can receive notifications from the user sending the commissions if payments are not received. I am not sure how many user connections would be required, please advise on the limitation of simultaneous user connection to the DB. This will include the design and look and feel of the site.