There’s a few different ways this works. The first way is addressed by your QuickBooks Office / Remote. That will give you remote access to the QuickBooks installation that lives within the server. However, you may wish to access your own desktop without regard to QuickBooks. This is something that you can do outside the server entirely. It does not require your server. However, it’s a common enough need that we wanted to help you understand the process.
There are of course commercial programs out there like TeamViewer, Splashtop and others which you can pay to accomplish this. However, you can have that kind of access for free by just connecting the dots we describe here.