如何在空的成员资格表中创建自己的密码？

public string EncodePassword(string pass, string salt)
{       
    byte[] bIn = Encoding.Unicode.GetBytes(pass);
    byte[] bSalt = Convert.FromBase64String(salt);
    byte[] bAll = new byte[bSalt.Length + bIn.Length];
    byte[] bRet = null;
    System.Buffer.BlockCopy(bSalt, 0, bAll, 0, bSalt.Length);
    System.Buffer.BlockCopy(bIn, 0, bAll, bSalt.Length, bIn.Length);
    System.Security.Cryptography.HashAlgorithm s = System.Security.Cryptography.HashAlgorithm.Create(Membership.HashAlgorithmType);
    bRet = s.ComputeHash(bAll);          
    return Convert.ToBase64String(bRet);
}

<membership>
  <providers>
    <clear />
    <add name=\"AspNetSqlMembershipProvider\" 
         type=\"System.Web.Security.SqlMembershipProvider, System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a\"
         connectionStringName=\"SQLConnectionString\"
         enablePasswordRetrieval=\"false\" 
         enablePasswordReset=\"true\" 
         requiresUniqueEmail=\"false\"
         requiresQuestionAndAnswer=\"false\" 
         minRequiredPasswordLength=\"3\" 
         minRequiredNonalphanumericCharacters=\"0\"
         applicationName=\"eShop\"           
         passwordFormat=\"Hashed\" />
  </providers>
</membership>

    password = EncodePassword(password, \"asas\" + password);    
    string userId = \"0\";
    SqlCommand c = new SqlCommand();
    c.Connection = con;
    cmd.CommandText = \"Select UserId From aspnet_Users Where UserName =\'\" + username + \"\'\";
    userId = ((int)cmd.ExecuteScalar()).ToString();
    cmd.CommandText = string.Empty;
    c.CommandText = \"insert InTo aspnet_Membership ([ApplicationId], [UserId], [Password], [PasswordSalt], [PasswordFormat]) \";
    c.CommandText += \"Values (2 , \" + userId + \",\'\" + password + \"\',\'\" + password + \"\', 1)\";
    c.ExecuteNonQuery();