You can work on your own book with contributed recipes from family and friends. To do this, click on the "Friends" button to bring up the invitation dialog.
Type in your email addresses for those that you'd like to invite. Remember to separate all of the email addresses with a comma (",").
Once you've entered your email addresses, you can modify the default message below that to personalize your message to your invitees.
When your message is done, click on invite. You'll get a verification message that your emails have been sent.
If you realize you want to invite more people afterwards, just repeat the process with your new invitees.
They'll get an email indicating with your message asking them to contribute recipes. After accepting the invitation, they'll join the cookbook project. They don't actually edit your book directly, but rather add recipes that are available for you to add into the book.
Here's the screen they will see.
Once they contribute recipes, you will see them available in your "Recipe Box". You will then be able to add them to your book.