Elite skills?

How do i get them?

and this one in particular i was looking at

http://guildwars.gameamp.com/guildwars/skill/313.php

Find a boss that has it, equip a signet of capture, make sure you have the right primary or secondary class, kill boss, use signet. Done!

http://gw.gamewikis.org/wiki/Elite_skill
and
http://gw.gamewikis.org/wiki/Hundred_Blades

hundred blades is a pretty bad elite by the way, but we dont really need to get into that.