Hi Mohammed,
If you're familiar with our SI suite of QWP then it works in a similar way with building charts using SQL Server.
Using the Configuration Editor tool you need to create a System and a Service that would connect to your K2 server and then in the qSIChartView you use the service to displays all K2 processes and from there you just define your X and Y axis.
Our documentation provides very good information about Quest Web Parts and K2 objects.Follow the documentation and if you still have questions please let me know and I'll be happy to answer them.