That's not specific question.
Maybe you wanna start looking here:
Data Warehouse Design Considerations
additionally to what Andreas and Romain said, I would highly recommend you to read the book "Delivering Business Intelligence with Microsoft SQL Server 2012" by Brian Larson. It is a beginners' book and it will guide you into building a solution from the beginning to the end (building the warehouse, questions to be asked, SSIS, SSAS, SSRS, Data Mining etc.).
Here is the link to the book: link.
Per aspera ad astra!
- Edited by Răzvan-Alexandru Duță Tuesday, September 03, 2013 11:11 AM