developing website of online car shopping

sir i m working on a project of developing a website of "online car shopping" i need ur assistance in order to complete my project plz guide me through that how can i build my website i mean tell me about necessary elements which i have to follow in order to complete my webpage. is there any sequence necessary while developing a web site of online car shopping?.and last how can i attract clients attention towards my webpage that every time my client comes to me whenever he or she want to buy a car for himself or herself. thank u sir if u know about all these things plz guide me through i will be very thankfull to u