That seems to be the right one babs :). Just remove the lead that goes from your PC monitor to your comptuer. Now put one side of the lead that your son bought into your TV, and the other into the computer. (just like you would connect your PC monitor to your comptuer, exactly the same place where you have to put your sons lead into the computer). Its not likely that the TV will automatically detect the input. On my TV there is a input option where it lists the following:
Side AV
Scart 1
Scart 2
PC
e.t.c
Try and find the option regarding the pc input, once selected you should now be able to see the screen on your TV.