Quantity wise Planning in Primavera 5.0???

How can I do Quantity wise planning in Primavera??
Quantity - i mean to say quantity of item
eg: 1000 cum concreting, say i want to do it in 3 months
i have given the activity duration as 3 months .. but how do i say i am planning to do this much qty in this particular month ...??
has it something to do with resource curves ??
any information regarding this would be helpful ..

Thanks in anticipation
Khanna