You can search across data in a number of ways in Datagraphs. Either within a specific dataset or across all of the datasets in a given account.
If you want to search across all data you can use the search box on the home screen (this is also called "Federated Search"). You do not have to specify a search term you can perform an empty query that will return you all data and allow you to navigate by facets. A free text search can be added, as well as a filter by facet, at any stage and in any combination.
Alternatively you can restrict a search to a specific dataset. You do this by selecting a specific dataset from the home screen. The search will then be scoped to that dataset alone and its associated facets. You can return to search scoped to all the datasets at any time by returning to the home screen.
See searching by facets for more information.