I am new to Belk, I need to pull last 6 months data of all incidents,change records associated with my group, help me to achieve this
Not sure if i understood your exact query. As you mentioned that you wanted to fetch last 6 month of data related to incident/change order associated with your group. Then you may try out of the box incident search page /Change Order search page and select details/summary report.
If these report doesnt solve then Try with BOXI reports.