Hi

How can I upload my iPod songs to PC

Connect the iPod to your PC using the supplied cable, then use the iTunes software.

I did, but still now I couldn't songs upload to PC through itunes.

Look up sharepod.com - that may be your answer

This iPod manage software can transfer the files from iPod to computer, iPod to iTunes, iPod to ipod:
iPod Transfer Software- How to transfer songs onto another computer from your ipod (http://www.ipodtransfer.net/how-to-transfer-ipod-file-with-ipod-transfer-software.html)