Some help on a 2.1 Speaker set up (connection output)?

The short answer to your question is that these speakers just won't work with that computer. Simple as that. They are passive speakers meaning that they are just speakers, nothing more. They have no amplifiers built into them as active speakers do and active speakers are what computer speakers are. Even if you were to get some kind of amplifier, such as a receiver, you still wouldn't be able to use that subwoofer with it because it too is a passive speaker and all modern receivers require an active subwoofer. You'd be far better off putting these speakers back in the loft and buying a set of modern, computer speakers.