I do not know how to set the program to alert me when it detects a virus in real time, not just when i scan the hard drive.
That is enabled by default. I suggest you read the help file and make yourself familiar with the things Avast is offereng the user.
It is set automatically, unless you change the settings. You will know, if you have your speakers on it will wake the dead.
There is a harmless anti-virus test that you can use - http://www.eicar.com/anti_virus_test_file.htm
You can tweak your avast installation changing the avast4.ini settings (see ‘Settings’ on my signature), disabling avast sounds or, better, don’t browse infected sites or receive infected mail ;D