How to use Replacement Path Variables to perform Date Calculations in the BEx Analyzer

Step by step procedure is available.
 the useful link which I refered :
http://teklink.co.uk/sap/sap-bi-bw-how-to-use-replacement-path-variables-to-perform-date-calculations-in-the-bex-analyzer/\\

http://www.sd-solutions.com/SAP-HCM-BW-Replacement-Path-Variables.html