Some speakers can be powered via the computer and some are powered via an outlet.
If they are self powered, then you should have one speaker that only has one wire attached to the other speak. And from the other speaker should have a wire that will get plugged into the computer speaker plug.
If there is a small round hole on the back of the speaker that has the wire that goes to the computer, then that would be for the power supply to get plugged into an outlet.
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