[wakerobin2]

Where does one enter one’s ACBL number on BBO?

[pilowsky]

From the home page, look at the line that says 'Featured Areas'.
Just below that, click on 'ACBL World'.
At the bottom of that page is a tab that says 'Add your ACBL number'.
Click on that.
Here, you can add or amend your number.
Or, click the link on this page that says 'join the ACBL' if you are not a member.

Now you will need to keep your wallet warm.