This image shows a portion of the Networking Advanced variables on the Create stack, Configure variables page.
This is one of five.

On the left there are steps indicating the workflow:
1 Stack information
2 Configure variables, which is in bold font to indicate it is the current page.
3 Review

Under Networking Advanced there are fields with sample text:
-VCN CIDR
-Name of Cloud Manager Subnet
-CIDR of Cloud Manager Subnet
-Name of Windows Client Subnet
-CIDR of Windows Client Subnet