You cannot manually create a cluster except for a small, single-node cluster you get on community. Also if there is inactivity it gets removed. 😞 

Go to the workspace section and create a new notebook on workspace. There may be one there from the dropdown menu at the top of the notebook. 

thanks for the quick reply. oh ☹️, they disabled option to create cluster.

If i create notebook and run it , explicitly cluster will not be created but it will work in the backend , am i right?