Please follow the blow steps to add other connectivity product in your Client Zone:
Click on Connectivity
At the Bottom left corner of the white screen click on "Sign up a new connectivity package"
A window will pop up and you need to chose the connectivity product you want to sign up for. In this case you would chose the "DSL Line"
Continue with the sign up process and the DSL line will be added to your Client Zone profile.
Through this process you can either sign up for a DSL ready line or a new convert.