To create a new topic inside a cluster from the extension, follow these steps:
Click the drop-down menu where all your clusters and topics are listed.
Find the cluster where you want to create a new topic.
Click the + button next to the cluster name.
Edit or save the topic name as needed.
Your new topic will be created inside that cluster.
If you forget this stop, don't worry - you can always just drag and drop it into the right cluster through the Dashboard.