What exactly did you buy? There aren't any "COM" slots on a motherboard. So I have no idea what you are doing.
In any case, I assume you bought some sort of card, and installed that card into your computer. You should simply have to power on the PC, as Windows boots, you should get the "found new hardware wizard". If Windows has drivers, it should install them and the card will be useable. If Windows doesn't have drivers, you will need to use the driver CD which should have come with the card. Install the drivers, and likely reboot. The card should then be useable.
In any case, I assume you bought some sort of card, and installed that card into your computer. You should simply have to power on the PC, as Windows boots, you should get the "found new hardware wizard". If Windows has drivers, it should install them and the card will be useable. If Windows doesn't have drivers, you will need to use the driver CD which should have come with the card. Install the drivers, and likely reboot. The card should then be useable.
