This article covers all the different ways content can be imported manually and automatically from spotify.
If "admin -> settings -> automation -> search method" is set to "spotify", you can simply use the main site search and any matching songs, albums and artists will be imported automatically and stored in your local database.
Channels can be set to automatically import specific content periodically (eg. top 50 tracks on spotify). For more details on channels see the article here.
Individual artists, albums, songs and playlists can be imported by spotify ID from admin area. For example, to import "queen", open "admin -> artists" page, click "new artist -> import artist", enter spotify ID and click import.
Note:
Spotify ID will be the last part on spotify url, for example 1dfeR4HaWDbWqFHLkxsg1d would be the id for this url: https://open.spotify.com/artist/1dfeR4HaWDbWqFHLkxsg1d
Related content will be imported automatically as well in many cases. For example:
importing artist (via search, ID or channel) will import artist's discography and a number of similar artists.
Importing album will import tracks and all artists for those tracks.
Radio pages will automatically import all displayed artists, albums and tracks.