Hi Mohit,
For report painter you need to follow all the steps in the sequential manner. If anything missed in middle can't run the report properly. Its difficult to explain all the step by step process.
Please follow the below thread and other links:
Report Painter with FI example....
Process Example: Creating a Report Writer Report (SAP Library - Report Painter / Report Writer)
http://help.sap.com/saphelp_erp60_sp/helpdata/en/5b/d22cee43c611d182b30000e829fbfe/content.htm
BR, Srinivas Salpala