ASP.NET

Can help me about to make online Shopping Website. My query is under:

1. How to add cart 
2. how to show product value in repeater (with Image) 
3. how to process billing.
4. what is way of return process  

Please suggest me my database is in linq (No SQL)  so Help me as well as earlier.

Thank You

List<Account> accts = new List<Account>();

protected void btnShowAccountDetails_Click(object sender, EventArgs e)
{
    StringBuilder acctDetails = new StringBuilder(); 
 
    if (Session["acctObjects"] != null)
    accts = (List<acct>)Session["acctObjects"];
    
    foreach(Account acct in accts)
    {
     acctDetails.Append("ID: "+ acct.Name + " Account ID: " + acct.AccountID + "<br/>");
    }   

    litCtrShowAccountDetails.Text = acctDetails.ToString();
}

protected void btnAddAcctount_Click(object sender, EventArgs e)
{   
    Account acct = new Account();
    StringBuilder acctDetails = new StringBuilder();
	 
    if (!String.IsNullOrEmpty(txtName.Text))
    {
	acct.Name = txtName.Text;	
    }
    else
    {
	//Display Error message
	ScriptManager.RegisterStartupScript(this, GetType(), "EmptyName", "EmptyNameAlert();", true);
    }

    if (!String.IsNullOrEmpty(txtAccountID.Text))
    {
	acct.AccountID = txtAccountID.Text;	
    }
    else
    {
	//Display Error message
	ScriptManager.RegisterStartupScript(this, GetType(), "EmptytAccountID", "EmptytAccountIDAlert();", true);
    }
  
    accts.Add(acct);
    Session["acctObjects"] = accts;
}