How do I upload video footage from my JVC Cybercam GR-DVL520 onto the computer?

JVC support is at http://support.jvc.com/consumer/support/index.jsp
The manual for your camera is at http://resources.jvc.com/Resources/00/00/98/LYT0869-001B.pdf

Connecting to a PC is covered in detail on page 65. You can use the supplied USB cable or a separate DV cable.

http://resources.jvc.com/Resources/00/00/98/LYT0869-001B.pdf

In short, connect the PC to the camcorder then set it to 'play'. A modern OS should autodetect the camera and allow you to make a copy of any movies on the PC in a variety of formats.

I believe you are trying to download video footage from your camcorder onto your pc. ( and not the other way around- from pc to camcorder).
If thats the case plug in your USB cable supplied with the camcorder onto your PC and which will register as a new drive on your system. For some cameras you need a special video capture card which needs to be plugged into your PC to allow video to be downloaded. An example is the IEE- firewire series. You will also require a simple video capture software to capture and save the video footage as a workable PC file. Try reading up on the brochure which came with your camera which I believe will provide more details. Normally video cams will come with such software and the necessary cables. Recent camcorders come with a harddisk & it is much simpler to download as such systems are recognized by a PC as just another new drive on the system. Try out the above and I believe you will be able to do it. Bye