trying to create new playlists on Windows 10 pc, how do I name a playlist other than Playlist?

When you click on New Playlist, it will be created and highlighted, so in theory, all you need to do its type in the new name.

However, if you miss the opportunity, all you need to do is double-click the new playlist name (usually Playlist, but in my case, because I already have one by that name, it's Playlist 2) and it will be highlighted in blue. Then you simply type in the new name. You can do this is the sidebar or in the right-hand window: