I want to localize my app, and I add French and Spanish to the target properties other than English
If you go to the "Info" pane of your project, you'll see a panel that shows your Deployment Target, Configurations and also the current localizations that you support (including a checkmark for "Use Base Internationalization"). Base Internationalization, b.t.w., allows you to have a single storyboard file that has different string files populating the string fields in the storyboard. It works for iOS 6 and newer.
When you start, it might look like this:
Here I've added Hindi as a language possibility:
And when you're done, you have the checkbox to choose from: