How to add music to my iPhone without deleting the music that is already on it?

So, my friend put some music on my iPhone a while ago and now that I'm trying to add my own music, all of the options I seem to be trying are telling me that adding my music would erase what he gave me. I would really prefer that not happen… Any suggestions?

What you have to do is transfer the songs you have in your phone to your iTunes.

When you plug your phone into your iTunes it should shown your device in the left column.
1. Right click on the device
2. Click transfer purchases in the drop menu
3.let them sync

When they sync then put all the songs you want into a playlist.
1. Command + N will give you a new playlist for an apple product (if not go to file- new playlist)
2. Add the songs by dragging them over from the library and dropping them into the playlist
3. Once you have all the songs you want click on your device again.
4.It will show your iPhone and right above it it will show you are on summary, go to the music tab.
5. Select the playlist(s) you want and then at the bottom right press sync.

If the message saying it will erase the songs comes up again don't worry about it because they are already in your playlist.

Hope this helps!