Iphone, how to sync new music without erasing everything else?

Help! I wanted to add a few new songs to my iphone and when I wanted to listen to it later, I noticed that all of my other 200 songs were gone. Did I miss something in the syncing process? Should I change my settings? I'm sure its something simple.

Ok. You are right, it is quite simple.

In iTunes, you can have various syncing settings.

I would highly suggest making a playing called Your Name's Playlist. Once you have done this, add all the songs you want into this playlist. Plug your iPhone in, when it appears in iTunes, there should be several tabs at the top that say Info, Music, Video. Go to the music tab, and change the default setting so that it syncs by selected playlists. Then, make sure that the tick by your playlist is ticked (this is all being done in the same window under the "Music" tab). Hit sync it the bottom right hand corner and all your songs should be on your iPhone. If you ever want add or delete songs, you can do so by dragging songs into the playlist or deleting songs from the playlist.