Add Source Levels to a Dimension
Source levels obtain values for their categories from columns in the Data Sources list. You can add source levels to a dimension either on the Dimension Map or in the Categories diagram.
Suppose the Region dimension of your sales model has three levels: Region, Country or Region, and Branch Name. You add sales representatives to the Region dimension by selecting the Sales Rep column from the Data Sources list and dragging it to the spot indicated in the following image.

Tip: You can create a default time dimension with
Year, Quarter and Month levels by setting the Data class on
the General tab of the Column property
sheet to Date and dragging the column to the Dimension
Map.