how do you add songs to itunes12.7.3.46 playlist

Hello and welcome to Apple Support Communities, danfromlilburn.
If I understand your post correctly, you are using a computer with Windows 10 and you'd like to add songs to a playlist in iTunes. I'm happy to help.
There are a couple of ways to add songs:

Create a playlist

1. Choose File > New > Playlist.

2. Type a name for the playlist.

3. To add items, do any of the following:

   • From anywhere in your iTunes library, drag an item to a playlist in the sidebar on the left.

     

   • Right-click an item, choose Add to Playlist, then choose a playlist.

Check out the full article here:
iTunes for Windows: Create a playlist

Let us know if that resolves this issue for you.
Thanks for using the Apple Support Communities. Take care.