How to transfer SOME OF THE SONGS from my Mac to my iPhone?

I don't want All the songs, just the ones I may or may not (depending on a WHOLE other question) have done the YouTube to Mp3 thing. How can I do it? And when I try to sync it, it says it will delete all the music I've already downloaded, so help?

And is the YouTube to Mp3 converter safe? What's 1 you use that works well? There's this song on YouTube I want on my library So BAD! Search "Give Me Sweets Hyper Blossom" and there's this one japanese song with these three girls dancing to the song.

THANKIES IN ADVANCE!

Tipard iPhone Transfer Pro for Mac can help you transfer any of your local files to iPhone with ease.