DynDNS user

[Sythos]

i'm getting an error on Dyndns client (integrated in an ASUS router), as password i'm using the "update key" from tunnel details (advanced tab), as user my full UserID from Mainpage (but guides and hwoto say "hex id", the ID i can see start with "tb" so isn't hex". Where can i find or setup my dyndns login data?