Leto,
Its really pretty easy, you migh screw up the first one or two, so practice with a piece of line that you can throw away. You need a specially designed needle. They ued to come with the spools of dacron, but you can buy them seperately. The needle has a hinged eye. You slip it through the hollow dacron as far as you want and then poke it through the side of the dacron. Then put the line into the eye and close the hinge and pull the line back though itself. Its easier to show you than describe it. If you go and buy a needle they come in an envelope that has instructions and diagrams on it.