Responsive website for entering promotional codes

We need a responsive website built so that our customers can enter their unique code, to be given a link to a download. We have the design for the website - we just need it putting into action. The website will need to have a homepage, terms and conditions and thank you page, along with a popup/ popover where the customer can enter their promo code to gain access to the download. The homepage will have three buttons that once clicked will open the popup/popover box to enter the customers code. Upon entering the code, they will be redirect to a thank you page, that will also generate the download of a file (each bottom, will be linked to a different 'thank you' page and file, i.e. 3 different pages). You do not need to worry about the download as this will be hosted externally, so if it can be setup so we can enter in the link details at a later date that would be excellent.