This is a link provided by avast to see if WebShield is working as it should be:
http://www.avast.com/eng/test-url-blocker.html(If you do not want to have the alert, do not click this link).
If you get a toaster pop-up, then it is working ok. It is safe to use and indicates avast has
blocked the threat.
As bob3160 said, this is the most important shield you
have to have.
[EDIT:] Avast Secureline VPN is
not free, but is offered on a 30-day trial basis. You'll need to provide credit or payment details to start the 30-day trial, after which you can cancel (watch for the automatic renewal feature in case you do not want it) or allow the trial to transfer into a full license for your machine.