In addition to Smart Add there are two commands that allow to add songs from the hard disc. Both of them add songs to the current folder.
Add Songs
To add songs from a single folder click Add Song(s) button and choose the songs you want to add.
Add Directory
Using Add Directory button allows you to add multiple CDG files from directory (or subdirectories). Navigate to the starting disc folder and click OK.
TIP: Use Smart Add to add songs from the hard disc, as it automatically names the songs and create folders.