Hi,
First of all you need to learn basic concepts of ASP.NET And C#. Before getting knowledge of the technology you can start analysis of your project. list down all the features you are going to implement.
As far as designing(UserInterface) is concern you can purchase some html template/download some free template. you can attach css/javascript/images from that template. Designing website from scratch and with such high graphics will take more time for you.
Now For development you can follow different architecture either
MVC/N-Tier/other. Also look into
Design Patterns[
^]. this will also gives you some idea about software designing.
EntityFramework is also very good practice to start with. you can also use
StoredProcedure in your project. As far as Performance is concern, you can use indexing in your database and paging in your gridView. Create your stored procedure to return only desired data instead of all data from the database.
Hope you start your new project with more planning.
Best luck
Thanks
-Amit Gajjar