as we a still transfering the portal to the dedicated servers, the Forum posting option will be enabled Mid of September 2017.
At that time, posting is enabled for users authenticated by the operational ESA Earth Observation Users Single Sign On (EO-SSO), which will be used for all personalized portal functionality of FS-TEP. Login to EO-SSO is provided on https://eo-sso-idp.eo.esa.int, to register yourself, please go to https://eo-sso-idp.eo.esa.int/idp/umsso20/registration
Login functionality to FS-TEP using EO-SSO will be enabled Mid of September. too.
Thank you very much for your patience!
The FS-TEP team