Not sure what the proper approach is, but here's what I've done:
Presuming your rig is the same as the Capri 22, you'll want to get some stainless wire from your local chandlery. Or you can use a strand from an old set of shrouds if you have it (that's what I use). You definitely need to use stainless, not something other metal that will cause electrolysis.
There should be a small hole in the tip of your spreader that you can pass a piece of the wire through. I usually take about 6 inches and poke it through so the wire sticks out evenly on both sides of the hole. I then poke the 2 ends through again so I've got a wrap around the tip of the spreader. I then take a single twist, at the end of the spreader, lay the shroud against it, and take 2-3 wraps around it with each end of the wire. Do not make it super snug as it needs to be able to move when you lower the mast. I bring the wires back to the spreader and "tie" it off, then trim the loose ends, making sure they're not sticking out so they'll tear the jib.
Hope this helps.