Thank you for posting and welcome to the Bose Community!
I take it you have a Wave Music System III, is that correct? You can identify this by looking at the bottom of the remote and it will have the system name.
If that is what you have, you can connect this to your computer with a 3.5mm to 3.5mm aux cable like this.
Once you connect one end to your computers headphone port and the other end to the AUX port on the back of the Wave Music System, then you would turn your Bose system onto the AUX selection by the remote and adjust your volume.