using system.exceptions namespace

Try 
  Piece of code ..
Catch objError as Exceptions
     display objError.message
Finally

try
{
 //set of code
}
catch(Exception1 e)
{
 //error display
}
catch(Exception2 e)
{
 //error display
}
finally
{
 //compulsory execution will be done here
}

In ASP.NET exception handling is achieved using the Try ? 
Catch ? Finally block. All the three are ASP.NET keywords 
and are used do exception handling. The try block encloses 
the statements that might throw an exception whereas catch 
block handles any exception if one exists. The finally 
block can be used for doing any clean up process. Any 
general ASP.NET exception forces the application to 
terminate without allowing the code to continue executing, 
resulting in an error page. 

<Script runat=server>
Public Page_Load(sender As Object, e As EventArgs)
{
try
{
// Statements that are can cause exception
}
catch(Type x)
{
// Statements to handle exception
}
finally
{
// Statement to clean up 
}
}
</Script>
Custorm Errors:
The default settings that is available in machine.config is 
as follows 
<customErrors mode="RemoteOnly"/>

In ASP.NET, we have three types of Error Handling.
1. Structured Level Error Handling (try..catch..finally 
block)
2. Page Level Error Handline 
3. Application Level Error Handling.