Question:
"Does the Eliminator Harness come with everything I need to attach the Quad handles?"

Answer:
No, the Elimnator Harness does not come with everything you need to attach the quad handles. You'll also need the Harness Fix to attach the handles.

Question:
"Could you explain how the harness works?"

Answer:
This depends on what you're going to use it for. I do kite jumping and kite lifting. In the case of the former I use the harness as if it were the seat on a playground swing. In the case of the latter,  use the harness as a means of attaching the kite to an anchor (my jeep), which means all I have to do is steer the kite. I should also tell you that my harness came without instructions so I learned by trial and error. You'll have to guess which harness will fit you best. I have a 35" waist and the XL fits me perfectly.
They say a picture is worth several thousand words, so here's to hoping you have a high speed connection for what I'm going to send you.

SEE Joe's Picture & Descriptions (might take a while to load)