Getting ebooks onto the Kobo Touch is easy, at least if they are in epub format or one of the other file formats that the Kobo recognizes. When you plug the KT into your computer via USB and touch Connect, it appears as a removable disk drive. You can copy book files onto it, then Eject and disconnect. The screen will say "Processing new content..." for a few seconds, and the new books you copied onto it will appear.
An even better way is to install the free ebook manager program Calibre on your Windows computer. It will show you the library on your Kobo when you connect it, and Calibre can easily convert any non-epub ebooks to a Kobo-compatible epub format.
Fortunately iBooks does use epub format by default, so books you export from iTunes will be in epub format. iTunes won't recognize the Kobo directly (like Calibre will), so you'll have to export the books from iTunes first, then copy them to the Kobo directly or using Calibre.