If you want to run your software with same width and
height as your monitor's width and height then
implement the following technique in your application-

The abstract class indicates that a class may be used
as a base class for other classes and is not instantiable.

One great job programmers do is to convert one type to
another type.there are 2 type of conversions.

Virtuemart 2 for joomla is a very good extension to sell products
through website.To add product manually by code, they have doc on
how to use the Api to achieve this, but it may be hard to implement
there Api to add product.So i show here how to do that without using
Api but the simpla way using sql queries -

It's a good practice to show orange border when you set focus to textbox.
also the border will stay for some seconds.this way user know
that they have to do task on that textbox.

It's a good idea to identify the errors at run time to detect
and handle it. .Net framework has built in mechanism for that.
these exceptions occurs because of user,logic and system errors.