You can do it two ways. First, cable line goes to input of box (cable in). Then output of box to VCR input. Then output of VCR to TV. TV must be set to channel 3. VCR also has to be set to channel 3. The down side to this set up is that you have to watch what you record.
If you want to watch one channel and record another, then you have to get a 2 way splitter. One leg goes to the cable box (in) then (out) back to the TV. The other leg of the spltter goes to the VCR in then use video cables (yellow,white,red) video out of the VCR goes into video 1 of the TV. Put tv on channel 3 and use the cable box. When you want to use the VCR switch TV to video 1. If you don't have any video inputs in that older model TV then the only other choice is a DVR cable box or a new TV set.