if there is an eye fixed into the end then simply tie the line to this.
if there is not then you have a few options..
whip an eye onto the end
or
you can get a "stonfo" type conector that you glue onto the end
or
this is one of those things that sounds complicated and is much harder to describe in words than it is to actualy show,
take two pices of silicone tube, one about 1/4 inch long that will be a snug fit 4-6in back from the tip, and another of 1in that will be a tight fit on the very tip.
thread these onto the line narrowest first, then with the line trapped in the tube slide the first one on, then twist the line round the tip 6-8 times, forming a spiral to the tip then push the other bit of tube on. I know this does not sound very secure but I can assure you it works ( may take a few goes, trial and error before you suss it !)
