You'll need to use a USB hub to connect more than one device to a single port. If you have a single USB port on your computer and need to use three USB devices, you need to first plug a hub into the computer. The hub will then have four or seven (or however many) ports available for you to plug in additional devices. Hubs can be daisy-chained to provide even more USB ports if needed.
This was first published in April 2003