Flashr comes with comprehensive documentation. This is automatically generated from the comments in the code using Natural Docs. The documentation is included in the Flashr download but you can also browse it online.
It is also useful to refer to flickr.com's own API documentation - sometimes this will make it clear why a certain aspect of Flashr works in a certain way.
If you can't find the answers you need in the documentation then please check out the other types of support.