When you first open up the app, it gives you a little mini-browser that you can surf websites with. You can go to any website with the browser, but the website I thought was most compatible with this app was Seeqpod.com.
Once I arrived at Seeqpod.com, I got a long list of song files that I could download for free. Once I confirmed the download, iDownload started downloading the files directly to my iPod. By the way, I only downloaded songs that I already owned; I had a suspicion that not doing so would result in breaking a copyright law or something.
The files downloaded quickly and easily, and I found that I could play them and access them from my iPod at any time. They were actually in the iPod, not in the application, as I thought they would be.
Next, I tried to share a file. The instructions told me to turn on file sharing on iDownload, then go to the web address they gave me from my computer. I tried to get to the web address a few times; it didn't work the first three or four times, but finally, finally, I was successful.
Instantly, I could see all my computer files on the screen of my iPod. I downloaded a file, and could access it from my iPod at any time (I was so excited!).