The Modem Chicken and the Egg Question: Newbie Alert

[J Simpson V21]

Hi
Thank you very much to Bill who noticed my error ( and to others for helpful
comments), when I typed it correctly, I got

> If it is not enabled in hardware, it will show:
> /dev/ttyS3, UART: unknown, Port: 0x02e8, IRQ: 3

Pete then suggested that:

> If needed, you can use setserial to change i/o & irq to match
> your hardware
> setings:
> setserial /dev/ttyS3 port 0x02e8 irq 3
> Have a look at "man seterial".

I really don't know how to do that and unfortunately the man setserial
didn't make much sense to me.

Could someone make it simpler?
Do I just type in setserial /dev/ttyS3 port 0x02e8 irq 3 ?
Do I need to know something more about my modem?  Am I going to have to open
up the box?

Regards
Janet