Do you want to add a line of data? If so, from the CSDS main menu, select 'Music | Edit Music Database'. This will display the Edit Music Database window. Now select 'Edit | Add new music file(s)'. This will insert a row for each music file you select. You can then use 'Edit | Edit hightlighted item' or the 'Edit' (pencil) button to edit the current row.
Do you want to add extra columns to the music database? Extra columns can not be added to the music database (without me changing the program and/or structure of the music database). If you have a need for a new column, let me know about it, and I'll consider adding it.
On the other hand, you change the size and order of the columns. You can use the mouse on the column headers to change the size, and to drag a column to a new position. This functionality is also available from the menu via 'Display | Column position and sizes'.
The 'Genre Flags' column is designed to be used to mark music selections as belonging to specific categories. The default flags are 'Patter', 'Singing call', 'Round', 'Line', and 'Sing-along'. You can add about 25 more if you'd like. Typical categories might include 'gospel', 'holiday', 'vocals', 'key change', 'crowd exciter', 'singing calls to learn', 'jazz', 'showtune', etc. You can add new flags via the menu 'Edit | Music Flags...'.
For personal data that can not be easily described using 'Flags', use the 'Comments' field.