What happens to old AccountRight Plus company file when upgrading?

I've downloaded the latest version of AccountRight and I need to upgrade my company file.

I have no idea what I'm doing! If I upgrade my company file, does it create a new company file? Will I still be able to open it in AccountRight Plus Version 19.6.1?

I really don't understand this whole MYOB upgrade thing at the moment. I'm not even sure if what I've downloaded will work. This is the page that I downloaded from: http://myob.com.au/business/download-accountright-1431309437816

Any ideas?

Thanks

Rachel