[Water Warrior 2]

The little chrome covers are just for show. Pry them up with anything that will do the job. A very small screw driver should do the trick.
The nut on the end of the bar end bolt is a metric thread. If I remember correctly it should have a shoulder on it. Sort of a built in washer design.. Most big box hardware stores should have them. Take the bolt with you for proper fitting size. The bar end has to be completely assembled before installation and is then tightened up to compress the rubber so it expands and grips the inside of the bar. The rubber is a tight fit and might need a shot of WD40 to help it slide in.
Keep in mind the bar end should not bind the throttle action when it is properly fitted and tightened. It is not to be used as a cruise control.
If you really feel adventurous you can loosen off the other side 2 or 3 turns of the screw and remove the entire bar end to see the exact placement of all the assorted pieces.
I was forewarned about undoing the screw entirely before removing the bar ends and it was a problem free job. The rubbers were snug fitting even when the screw was loosened but a bit of force and wiggling helped a bunch.