Hi Sadia,
There were good number of documents available related to loading data to 0IC_C03 cube. A basic search on SCN will give you the necessary documents.
Also please refer this below links too.
http://scn.sap.com/docs/DOC-41821
http://scn.sap.com/thread/2083026
You can go ahead by using Anshus' reply wherein which you can come across step by step approach with screenshots of loading data to 0IC_C03 cube or else simple approach of Arshiyans' reply.
Thanks,
Karan Lokesh.