Above you see a screenshot of Service Bus management in the old portal and below a screenshot for the new portal.
You will find more on working with relays using the new portal through Trying Out the New Windows Azure Portal Support for Relay Services blog post by Richard Seroter. On each tab you will find + NEW button on the left hand corner below. If you click NEW a dialog will appear.
Now you have to ability to create a new queue, topic or relay. You can create a new queue for instance through QUICK CREATE with default settings or CUSTOM CREATE with custom settings. If you for instance want to create a custom queue you can click CUSTOM CREATE. A Wizard will start and you will have to fill in a Queue name, region (i.e. data center), subscription (one you create when signing up for Azure) and Namespace (which can be created through Service Bus service view by clicking CREATE button in menu below).
Next step is configuring the queue by determining the max size, message time to live, move messages to dead letter queue, lock duration, duplication detection and enable session.
If you now click the check mark button the queue will be provisioned.
As you can see the queue is created and visible in the portal. You can click the newly created queue and see some characteristics in a dashboard.
You have to ability now to view the connection string of the queue, delete, disable it or view the access key. By click the access key a dialog will pop up showing you the connection string, default issuer, default key and link to ACS Management Portal.
Finally I also like to point out that you can also manage the service bus through Visual Studio 2012, or Service Bus Explorer. I did a comparison between the too in my Visual Studio Service Bus Explorer versus Standalone Service Bus Explorer blog post.