Before I can accept you into the "Captains - KoG" User Group, I need you to update your "GamerTag" associated with your Xiled Gaming profile and request a new Username / Login name to match your new GamerTag.
To update your "GamerTag", click "About Me" on your profile (directly above), click the yellow pencil next to "GamerTag", update it, then "Save".
To request a new Username / Login Name, click "Help Desk" in the top right corner, click "Request Login Name Change", type your new GamerTag, then click "Request New Username".