scanning with Avast 4 home

I downloaded and installed Avast4 home and registered. I can’t seem to get it to scan my computer, I selected the type of scan then when I clicked on the right looking arrow nothing happened neither is anything happen when I used the menu how do I get this to work?

Wellcome Stephen…
Did you select an area to be scanned, I mean, the hard disks, the floppy or CD, a special folder… You have icons to do it 8)

I hadn’t done that. Thanks for the reply it is scanning now