all asp.net handlers implement the interface of IHttpHandler located
in the namespace of System.Web.ISAPI(Internet server application
programming interface) extensions are somehow analogous to Handlers.

upgrading dnn website to upper version is easy.one
have to follow the following steps to do upgrading.

you can use online paypal buy button in your page
for receiving online paypal payment.when users click
this buy button they will enter in payment page
for payment.

It's nice to show cool gradient color as a
background color of the form in c#.net desktop
application.you can set different colors.

command objects use parameters for passing values
to sql statements for type cheking,validation,guarding
against SQL injection attacks,etc.so its a good practice
to use command parameters to sql statements.