When you first register, you will see a hyperlink field in your profile with the label "External profile." This link is automatically generated, and points to your user page on the previous CS site.

If you wish to override the address for this link, edit your profile and scroll down to the "External profile" field, which is a text field that by default will either be empty or have the text value 'default' in it.

Set this value to a fully qualified URL, and when you save your profile and view it, it will use your value for the hyperlink. If you wish to disable the hyperlink, fill in the value 'none' for this field.