Every report is driven by an XML file, known as a Report Definition. Most of the web part configuration is carried out via the web part's tool pane; however, you may require even more flexibility and want to create your own reports, for example if you added extra columns to BrightWork or SharePoint lists you would need to create your own report to be able to report off these columns. The Report Editor makes this a relatively easy task.
There are three possible report locations:
BrightWork Server Gallery
The BrightWork Server Gallery is where the generic reports and the template reports shipped with BrightWork are stored. Reports in this location are accessible to every site collection on the server.
BrightWork Reporter Library
A BrightWork Reporter Library exists at the top of every BrightWork site collection. This is where custom reports (i.e. ones you make yourself) are stored. See About BrightWork Reporter Library for more information. Reports in this location are accessible to every site in the site collection.
Custom Location
You can also save a report definition file in a SharePoint document library (for example another BrightWork Reporter Library). This is a useful option if you want to share the same custom report across multiple site collections. You will need to ensure that all the users who will be viewing the report have access to this library.