If the digital pictures are already downloaded to my PC, how are they then uploaded into Roxio to create a cd that will be able to be run through a TV?

First, your subject line states 'dvd' but your message says 'cd'....which do you want? In reality, you can make a photo cd or dvd but playing both on a set top player is the problem.
Basically, you import your jpeg files into a project. Videowave is best suited for this and gives you the most control.