To add on to what @D. Kroone stated, you need to create a custom template first as you can't change the ones delivered by SAP, second you need to hit the 'Change Settings' button to allow for changing the default time of 15 mins to what you want; but you can also only have it set to only fire on week days or perhaps just weekends (if you check the 'Advanced' box these selections will become visible).
And if your Windows server has multiple drives in it you can define specific drives that you want the metric to cover vs all the drives; in some cases the C:\ may be covered by the server team and your responsibility falls on the D:\ (aka the metric group variant)
Here is the screenshot that I pre-pared before seeing that D. Kroone beat me to the punch:
