Previously, you went to the Cordis site for this. However, this will no longer be updated. Unfortunately, the Cordis site is not redirecting users to the Participant Portal. Great. However, you do still have to go to the Cordis site for the legal documents and guidance. So it looks like the EC's made it ever so slightly more complicated and labyrinthine to apply to the Framework Programme.
However, I'm sure this is a minor glitch, and that they'll iron this out. I mean, this is the European Commission, actioned with coordinating the workings of 27 member states in 23 different official languages. What could possibly go wrong?