Well you can’t, really, unless all of that music was on your computer in the first place. Apple doesn’t want everyone sharing music with everyone else I suppose, so you can put music on an iPod from a computer, but not on a computer from an iPod.
Yep. Plug in your iPod, go into whatever drive your iPod is plugged into, choose to show all hidden folders. Go into your hidden file and you should know where to go from there. Your music will be broken down into multiple folders and your music files will be named with random letters (I.e. XZYB). Google or search on YouTube for a more in depth explaination. You don’t need to download any software