Look at about 2:57 into this video
https://www.youtube.com/watch?v=VWBSySwXRtA&t=184sThere are three other videos as well, one of which might show it more clearly.
It is very simple, You have to have the line going from the jib head grommet up to the swivel bottom (so it swivels with the forestay). You can add a bow shackle to make it easier to attach to the forestay eye since the swivel may not have space for two attachments. I suggest using dyneema since it doesn't stretch much, but you can use something else that doesn't break readily.
Try it out on the ground at least once before using it for sailing.