Can you please tell me the procedure of how to load data from SAP R/3 into BW system?
Actually this question is more related with BW rather than SEM, but I'll explain the procedure briefly. In order to load data from R/3 system into BW, (assuming that you R/3 system is defined as source system in your BW system) you should first maintain certain settings on R/3 side. First identify the application component from which you want to transfer data i.e. FI-AP. Activate the standard business content maser and transactional data datasources (transaction RSA5). Then, replicate these datasources in your BW system and create infosource(s) and maintain transfer rules for proper field/infoobject mappings. After you created update rules for your data targets, create infopackage for each datasource. Finally schedule the infopackage with desired selection options to load the data. At high level process works as described above, there are some detailed settings and you can find information about the details in SAP help.