Where did my old songs go?

Hi, for the first time in my life I have an iPhone and it is the older 3G model, I bought it second hand just to give it a try and then later decide if I will want to buy a better brand new one 3GS or not, I am enjoying it so far but I have a huge question mark in my mind so here it goes:

I already had a macbook before the iphone, as the iphone was not brand new it came with lots of songs and other stuff, yesterday I created an iTunes account for myself and clicked on sync on the iTunes then all the music that was on the iphone was deleted (which is good) but I wanted to find out where did they go as I don't want them on my macbook either...

Will you please help me with that info?

Thanks

Thomas - A Brazilian in South Africa :)