Sophos AV requires almost no interaction on your part. Its virus database is updated once an hour, automatically (laptop users are updated instantly when their computer gets a valid network connection).
If Sophos detects a virus you will see a dialog box pop up on your screen similar to the following:
As you can see in the example above, this particular file was just a standalone virus and Sophos automatically deleted it. If this was a file that was infected, you would have received a similar notice that the file has been disinfected. The only action you need to take is to click OK to confirm the message.