In the step1 of report builder, i chosed one dimension. and in step2, i can add only one dimension as breakdown. how i can add more dimensions?
In the step#2, you can add multiple dimensions as shown below.
Also, I would like to inform you that if you need to apply multiple break downs then use the dimension with the fewer number of line items first followed by the one which has more number of line items.
Hope this helps.
Report Builder has limitations in terms of breakdowns. If you want more breakdowns you'd rather want to use Data Warehouse which does not have this restriction.
You need to select Dimensions next to Metric on Step 2 of request wizard as shown below: