Can't get trough to where?
Here's the answer in any case.
How do I register for SAP Service Marketplace
You'll need an S User ID to login to SAP Service Marketplace: these are issued to SAP customers and partners only.
Unfortunately you won't be able to gain access unless via a public account. However, please you'll find a wealth of learning and practice resources in other places, such as SCN. Visit Getting Started with SCN.