How to add songs to an existing playlist in iTunes 12?

Hey Scott Wilson Design Studio,

To add more songs to an existing playlist, use the steps on this help page - Create a playlist - iTunes Help

Specifically -

Edit a playlist

Select the playlist and do any of the following:

Add items: Click Add To above the playlist, and drag items to the playlist.

And

Quickly add an item to a playlist

1. From anywhere in your iTunes library, begin dragging the item (or items) you want to add.

   A pane with a list of playlists appears on the left.

2. Drag the item to a playlist in the list.

   

Tip: You can also move the pointer over an item, click , choose Add To, and click a playlist.

Thanks for using Apple Support Communities.

Happy computing.

If you have any trouble dragging a song into a list, it's likely because you're dealing with a smart playlist -- the ones with a gear symbol beside them. You can't add songs manually to this kind of list. But you can look at the rules that define the list by selecting it and then clicking "Edit Playlist" in the upper right of playlist pane.

For example, there's a list called 90's Music that apparently came pre-installed with iTunes, and the main rule is Year > is in the range > 1990 to 1999. So you can add a song to this list by selecting the song, then File > Get Info, and typing a date within this range into the Year field.