Then the accounts should already be linked properly and you don't need to worry about the existing account stuff.
You can view your characters by selecting the game off the My Games tab:
If the game isn't there, click on the Register Games link and select the Xbox version (you'll need the UPC code). Then click on the My Games Xbox link to view your character profile or click on Xbox player profile link on the register games link.
In my experience, the character profile stuff is very iffy. Sometimes it updates quickly, sometimes it takes forever (weeks), and sometimes it updates outdated info. If your character is still not popping up, make sure you have the correct firewall ports open.
If its still not updating, then its probably not on your end and something on BW's end.