Chapter 2 states:
12. Navigate to your sharepoint online site, and then click the New App to Deploy Link.
I can not find this link. All I see is apps you can add . Has this changed since the book was published?

Hi,

If you're in your development site that you created previously, and click the Apps in Testing link on the leftside, the '+ new app to deploy' is there :-)

Tamz

P.S, I know this is pretty late in the game, but could help other :)
You could also do the following
1) Go to your sharepoint admin site (https://<your_organization_name>-admin.sharepoint.com
2) Click "Apps" on the left hand navigation pane
3) Add App catalog
4) Upload your app to this app catalog and this way it would be available for all of your sites to add.