Designing an eCommerce website for photos sharing (OpenCart)

Hi. Website Idea: It's An e-commerce website that provide images with different categories from different users. Users can sign up (Freely) to have an account ( and before they sign up to the website they should agree on the agreements and the policy as well ) so they can upload their images to earn money from it whenever their images sold. First of all I'd like to use OpenCart platform. What I Need? 1- Designing a beautiful, and simple interface for the website. - Home page: Header, navigation bar, slider, image thumbnails, and footer as most of website on the web 2.0 - Header will contain: 1-Area for website logo. 2- Search bar. 3- Other stuff that plugged in in every OpenCart theme such as: My cart, Sign up and log in, My Account, and so on. - Navigation bar: I want it to be simple, attractive, easy to use from any user and for us we want it to add tabs as we want ( I mean that we don't want it to be specific 3 or 4 that we can't add or remove tabs) -Slider: We want it to be between medium and large so we can show any instructions or announcement clearly. -Image thumbnails: This feature comes as a plug in with OpenCart. but from you, we need the thumbnails to be beautiful and clear because it's the main thing in the website idea. -Footer: Simple and beautiful footer that contain: follow us on twitter, be a fan on facebook ( and the button to like ). The system we want is similar to [login to view URL] system Each member has an account and profile that has his/her photos and there will be to option for the one who buy ( as what’s in themeforest ) : 1- Regular Licence 2- Extended Licence We want also different ways to sort the photos on the website ( on the home page and in every category tab from the navigation bar ) as here for example: [login to view URL] -Colors: We want it to be flexible so we can change it when ever we want. Thank you