How do I convert from Password Safe to KeePass format so I can store attachments?

There are a few ways to do this. If you have access to a PC you can use Password Safe and KeePass to export/import. This is described here:

Switching from Password Safe to Keepass

Another way is to use Strongbox on Mac. You can copy and paste items from a Password Safe database into a KeePass database and Strongbox will handle the conversion for you.