SSAS FACT TABLE utc column how to do date dimension and then time dimension

Hi Everyone

My fact table has data from 2005 till 2012 in this order

2006-02-01 00:00:00.000
2006-02-01 00:15:00.000
2006-02-01 00:30:00.000
2006-02-01 00:45:00.000
2006-02-01 01:00:00.000
2006-02-01 01:15:00.000
2006-02-01 01:30:00.000
2006-02-01 01:45:00.000
2006-02-01 02:00:00.000

Seperated by 15 minutes, how can I go about creating date and time dimensions, Do I need to create seperate  Date Dimension and time dimensions or should I create one dimension with date and time both.

Please help, I need to get it done ASAP and I am new to SSAS.

Thanks

-Sarah