3 PCs

I just signed up and it said I could activate Avast on 3 PCs. How do I put this on my other PCs?

same way you did on first … download, install and insert license

remeber to remove any previous used AV before you install avast
instructions here http://www.avast.com/faq.php?article=AVKB11#artTitle

avast FAQ http://www.avast.com/faq.php
FAQ videos http://www.avast.com/faq.php?q=video#searchForm