How to delete music from my iPhone?

I'm just wondering as I have never had one before and just bought a 3G. I can't find a way to delete music from it. I know that I'm supposed to connect to iTunes. Do I connect from the phone or PC? And then what do I click after connecting? I know I probably sound stupid but I'm really bad with technology.

I followed the instructions on syncing it but when I plug it in for some reason iTunes doesn't recognise it and the devices button does not appear on the side.

There are 2 ways:

1. From The iphone: for every song / item that you want to delete, on the list of songs, swipe the song to the right (same was as if you're unlocking your phone) - A "delete" option will come up - you can use this to delete most things on your phone

2. Delete the songs on the iTunes on your PC, then sync the phone with your itunes - the changes will duplicate to your phone