It's a good idea to use a class say gateway where all
database access codes will be written.in this gateway class
you will implement db connection as follows -

first create another class -

It's required that you configure your joomla SMTP settings so that joomla is able to send
email when user registered or different mailing functions works for other components and modules
like k2, CB....
In this post i show how to configure joomla 2.5/3 smtp settings properly.

if you are participating in a project of a
course,assignment,others on c#.net or asp.net
or may be others then you should follow the
steps for finishing the project successfully.

it is possible to run Application.Run twice in csharp
application.the following example shows that.it's a
example to create login to access the application.

The great control in the asp.net ajax is the update
panel control.it can be added to almost every
asp.net page almost magically.this control when
used with a ScriptManager permits a programmer to
use partial rendering(a technique by which many
sections of page updated partially without reloading
the entire page).

namespaces is a old concept in c# programming.both
java and c# uses this concept.a namespace is act like
a 'wrapper' around one or many elements which gives
them uniqueness.