how to block user after 3 invalid login attempts

int NoOfLoginAttempt = 0;
       private void btnLogin_Click(object sender, EventArgs e)
       {
          //Get the User name & Password from the text box
           //Connect to database and get the user details
          if(FOUND )
          {
               if(Password is matched)
               {
                   if(NoOfLoginAttempt ==3)
                   {
                       //connect to database and set the blockFlag=true;
                       //Inform the user that, your account is blocked.
                   }
                   else
                   {

                       NoOfLoginAttempt++;
                       //Show message box to usr to re-enter the password again
                   }
               }
          }
       else
        {
           //show the message box "user not exist"
       }
   }