There are two privacy settings when adding friends on Howbout:

1. Sharing your calendar means friends can view your Howbout calendar (and any external calendars you've decided to share), including your event title and header.
2. Not sharing your calendar with friends means they can't see your calendar or event details, but they can see your availability. 

One benefit of creating events directly on Howbout is that you can make any event 'Private' (so that your friends can't see the name or details of an event or 'Invisible' (so they see absolutely nothing). This gives you extra privacy even if you're sharing your calendar with them.