Hi,
Those 2 links are just the brief examples on how to interface master and slave Xbee devices using Arduino. You can always ask Mr Google for more info!
You can try search for Xbee master and slave communication topic, I am sure there are a lot of examples.
Regarding getRemoteAddress64().getMsb() this kind of 'thing', actually it is a function and I strongly suggest you should study what does it use for and how to use it. We should at least understand what does each line of the coding is for, so we can make modification later on more easily, am I right? Yet again don't forget Internet will always be right there for you to search for this getRemoteAddress64().getMsb() stuff! This will help you in learning and exploring.