You have to copy everything into your iTunes program, from whence you upload it to the iPod--
but then you can organize things into playlists/folders of whatever kind you want, then and upload them to the iPod.

However, whether you want it or not, the iPod will also organize everything into Artist, Album, Genre, Song menus that you can pull down and search or simply shuffle. You can also upload photos, podcasts, and often, videos, depending on the model.

One thing to note--you can upload to your iPod, but, for reasons known only to the Apple Marketing people, iTunes is set it up so you can't download from the iPod, so you have to keep everything that is on your iPod on your computer, as well. There is at least one program that you can get(though not from Apple) that allows you to download. There are also a lot of folks on the internet who dedicate their lives to finding ways to do what they want on the iPod.

As a naturally cheap person, I have found that it is often a good idea to check the on-line Apple Store for "refurbished" stuff(which is often really "open box" or store demo)--it can sometimes be had for a tidy discount.   However, I tend to follow the dictum "If it's not 50% off, it's not on sale." 16% off the original "new" list price for a refurb is not a deal.