The photos seem to be very low quality (such as when you try to wind up the brightness on the editor it goes very grainy or something!)
I’m not surprised, considering the amazing progress at noise reduction and better light sensitivity that has been made since 2006. It’s likely that you can do some better with techniques such as “expose to the right”, but that old camera is going to give noisier results than a modern camera, period.
Does the camera come with a USB cable for connecting to a PC? If not, you’ll need a CF card reader. Usually you don’t need any special software for copying photos to your computer: just use your file browser to select all of the photos on the camera card and copy them to a folder on your computer’s hard drive. Are you on a Windows computer?
If the photos are turning out too dark, make sure you’re on “Auto” mode. The shutter speed or aperture might be adjusted wrong, causing the photos to turn out underexposed. Auto will let the camera select the proper exposure, and you should get better results.
Keep in mind that with a DSLR “what you see” through the viewfinder is not “what you get” when you press the shutter button as far as exposure is concerned. If you’re used to a point and shoot camera with live view and automatic exposure preview it can take a little while to get used to that. 🙂
Blessings Captured’s idea is a good one. Here’s a link to the owner’s manual for the 30D. https://canoncanada.custhelp.com/app/answers/answer_view/a_id/1036444/~/eos-30d-instruction-manual