Yes, Jaspersoft is the tool used to modify, or create custom reports.
The Bright Pattern Contact Center Custom Reporting Tutorial explains how you can create custom report templates for your Bright Pattern Contact Center solution.
The first two sections of this tutorial describe how to configure the TIBCO Jaspersoft Studio application to customize report templates. The last section describes an alternative way to export custom data sets from the Reporting Database in CSV format using BPXML templates.
The following resources are recommended as a starting point for learning the Jasper Reports syntax and the Jaspersoft Studio visual editor: