classified site create using sharepoint
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I want create one classified site for example http://www.adtoad.com/,www.sulekha.com,first i want create login
page.one login page three type authetication required
                                          1)admin-this login have all permission add,update,deletet the product
                                          2)vender-only add the product not delete,edit option is there
                                          3)end uer-only visit if u want to buy the product then click the product 
                                                  after that one payment gateway,all product related information 
                                                  is avialbe in this site. 
  
HOw to create in sharepoint site 2010 please give me idea,If any sample code paste here.if any refernce site give me
                                                 
