Before digging into the XML behind dashboards, it may be a good idea to install the app Splunk UI examples app for 4.1+, available at Splunkbase (see Chapter 8, Working with Apps, for information about Splunkbase). The examples provided in this app give a good overview of the features available in both simplified XML and advanced XML dashboards.
The simplest way to find this app is from the default Splunk home screen by clicking on Splunk Apps.