cant see namespaces in my code

Hi,
I am learning asp.net and I have visual studio enterprise architect installed. As a prerequisite I had teh .net framework installed. the os is win2k server. it wont install active directory but this is because (i think) i dont have a network card.
the problem is this:
when I run a sample application in visual studio.net, that sends an email when u enter your name and email address on a form and click send button, it comes up with an error - cant override the new SMTPMail () method as it is private??? This is a sample application so it should run fine. the system.web.mail namespace is imported and this contains the smtpmail () method which is a public method, not private. i had the same problem running another sample application that uses ado.net. it seems like the class library is the .net framework cannot be seen by visual studio .net...
do i need to specify its location as a classpath environment variable like you would with java? or is there something i missed...
thanks!
Priscilla