Here is a more recent link to the documentation for Dynatrace AppMon 6.5; https://community.dynatrace.com/community/display/DOCDT65/Web+Dashboards
The link you provided goes to Dynatrace AppMon 6.2 which is already a bit outdated. Still good - but not most recent 🙂
I suggest you also check out the YouTube Tutorials that we have recorded where we show how to build dashboards with Dynatrace AppMon. this one is a good one to start: https://www.youtube.com/watch?v=Xw_NVYyun7k&t=763s...