A good start would be changing your password and maybe even request to the Admins that they change your User ID.
Just got an alert that myninfo was on a black market site and the only thing taken was MyFICO identity. What does that mean for me and what should I do?
The myFICO login and password can be changed from the myFICO dashboard.
Using the desktop site, you get there by clicking "My Account" in the far right-top corner of the screen. From there click on your own name in the far right-top corner, and you can change both your user ID as well as your password yourself.
Note that your myFICO forums member name (that is public) is separate from the myFICO user ID, and while the two can be the same they don't have to be. Also note that if you want to change your public forums member name a forums moderator can do that for you.