Today, by far the best way to learn <<anything>> is to “look for an existing example ... not just a demo, but an example of a real thing ... then
reverse engineer figure out how it works.” Github is an excellent resource for doing that, although not the only one. I have also found that it is very beneficial to “use the Source, Luke!” In other words, look through the actual source-code of <<Dancer>>. Very often, you will find comments in that source-code which give you strong clues as to “the designer’s intent.”
Maybe the very-most important lesson to learn is that ... you are not the first. There are, by now, thousands of web sites that have been implemented using <<Dancer>> and the complete source-code to many of them can probably somewhere be found. Therefore, you do not have to start at ground-zero on anything, and ground-zero is never (these days) the right place to start.