Development of a website in php

Simple Website to simplify internal invoice processes. A company hires freelancers for different events and want that freelancers uses that website to create their invoices. The website should be developed in HTML, php, Ajax, jQuery, mySQL There is only a login page as front end. Everything is displayed in the back end. Menus are - User administration - Services of the freelancers - Event management - Archive with created invoices (PDF files), which can be downloaded Functions: Admin user can manage (create, edit, delete, activates, deactivates) users, services. Users with standard data (name, adres, tax#, role, login, password). Services with ID, title, description, price, datetime, valid until etc. Admin user creates a freelance user account and sends a link of that account to the freelancer. Freelancer logs in and creates his invoice by using a form with several input, dropdown, checkbox fields. Only the services which are allowed can be chosen and the prices are fix. After creation of that invoice by filling the form, an email is send to the admin user "Freelancer had created an invoice, please check". When everyhing is OK, the invoice is accepted by the admin user and a PDF file should be created and send to the freelancer. That invoice should be displayed in the user account for downloading later, if needed. Freelancers should create their invoices at latest 8 weeks after a quarter. 2 weeks before a reminder email should be send automatically.