How do I add songs to Apple Music on my iPhone?

I don’t fully understand the question, but I’ll do my best to answer:

• If you want to purchase music, you’ll need Apple Music membership, then you can search for a song and buy it
• If you want to install a file into Apple Music for iOS, you’ll need to put the file in Apple Music on your Mac or iTunes for Windows. Then, you plug your phone into your computer and sync media. When plugged in, your phone’s name should appear in iTunes/Apple Music.