Now wrap the serving with lots of tension. The string will twist and you should notice that the right side gets twisted tighter and the left side more loose. While wrapping apply as much pressure to the serving tool to push the wrapping to the right. You are trying to have the serving wraps applied tightly against each other. Wrap for about an inch and a half or so and stop. Now cut off the tag end. You'll find that the string snuggles into the groove of the tool which protects your project from your knife. Cut it as close to the serving wrap as possible.
I can't explain how much tension to use but experience will guide you. Use as much as you can without twisting the string to death but enough to turn the string a couple of turns.