Hello,
The OpenFlashCharts library we added is so far only used by the RecordBrowser Reports module. This module is utilized by, for instance, SalesOpportunity Reports. When viewing the SalesOpportunity reports, you can switch to charts view, showing you various graphs based on this report.
We have plans to create additional reports and applets for various modules, but it's little further down the line.
If you are interested in utilizing the OpenFlashCharts yourself, however, then you can either use the RecordBrowser Reports module (see SalesOpportunities Report module for hints) which will be probably a bit easier, or you can use OpenFlashCharts directly, in which case RecordBrowser Reports has the appropriate code to look up.
Hope this answers your question,
Arek