Q: how do I sync all three of my apple products?

What are the Apple products (iOS devices, computers, combination of both ?), and what do you want to sync e.g. is that syncing content from a computer's iTunes to them, or keeping things such as contact, Safari bookmarks synced between them ?

To sync content via iTunes : Sync your iPhone, iPad, or iPod touch with iTunes on your computer using USB - Apple Support

If you mean syncing contacts etc through iCloud : http://www.apple.com/icloud/