Thread "Creating Main Menu Top Link to external web page with dynamic parameter"

I want to link into external web page by passing username or user_id as a parameter in Main Menu Top item using Link type.
i'm trying to use {username} as a variable to pass in Link text input, but it is not allowed.
what is the right way to pass a user_id parameter via this link?

btw, i'm using ILIAS 7.19 right now.