Check out the docs:
http://ez.no/ez_publish/documentation/reference/data_fetching/content/list http://ez.no/ez_publish/documentation/reference/data_fetching/content/node
If you don't know the node-id I'll suggest using the content list fetch, and supply it with the limit attribute (limit, 1) and do a proper sort_by to get the node you want at "the top".
If you know the node-id {fetch('content', 'node', hash(node_id, [nodeID]))} should do the trick.