I don't know much about the iPhone , this is my first time to use it and how I wish I had a good experience
I'm assuming Samsung has the ability to copy music from phone to USB flashdrive or microSD memory card. From there, copy the music to your computer.
Install the latest free iTunes software on your computer. Launch iTunes. Go to something like File, Add Files to Library, browse to the folder on your computer that has the music. Select all then press ok.
Plug Lightning to USB cable from iPhone to computer. With iTunes still open on the computer, it should detect your iPhone and the iPhone will ask you if you want to "trust" the computer. Press yes. In iTunes, the left column should now show the name of your iPhone. In iTunes, under Playlists, create new playlist, in music section, select whatever songs, right click, add to playlist. Click on playlist, select whatever songs, drag them to the left column and drop them on your iPhone, which will then copy to the iPhone.
In iPhone, press the musical note icon for Music. Your songs should then be in there under Recently Added. From there, you can make and edit playlists either via Playlists or via Songs where you press the "..." and pick add to playlist.