The required Version and Build numbers you add to Xcode make it into your app’s Main Bundle. You can retrieve those values from the Main Bundle and use them in your app.
// set version and build fields from bundle
NSString *version = [[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleShortVersionString"];
NSString *build = [[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleVersion"];
// display in your own labels
self.versionLabel.text = version;
self.buildLabel.text = build;
iTunes Connect reads both of these. Your “new version” is what’s displayed in the App Store, while the build is a more arbitrary thing you can set yourself.
Note that both values are floats, and that you need to increase them with every version. If you decrease either of them, iTunes Connect will complain next time you submit a build.