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