I use my soundcard for midi input. You may be able to use USB but I know nothing about that.
You need a special cable with the normal midi connection (5 pin in a semi-circular arrangement) at drum machine end and a 14 (or some such number) pin square for the soundcard. These leads come with the soundcard or can be bought retail. Midi drivers will have to be installed and any software you're using will have to be configured to recieve midi messages. Your drum machine will default output on midi channel 10.