You'll need (2) digital-to-analog converter boxes to be able to watch one show, while recording another. One
dtv converter would have to be plugged in to the input of your VCR (and then output from the VCR by coax or RCA cable to one input of your TV), and the other
dtv converter would be plugged into the second input (if available) on your TV.
Let us know if you need help with the setup.