How do I create Usage Profile...

I'm playing with the Usage Profiles associated with Capacity Planning. I've manage to create my own profile - but as I understand it its possible to use specify my own settings for what I feel a small, medium and large VM would constitute. Rather than basing those predictions on what we have, I want to assume that my new guest OSes are going be substantially different from all previous VMs we have had so far - with switch to Windows 2012 R2 and Windows 8.1 I want to see how many of those GoS I could run...

I just don't see where I would 'edit" those parameters in the profile...???

Regards

Lou