The first step in accessing Bridges is to request an XSEDE account. In the upper left hand corner, under 'Get Started on XSEDE' Click 'Create and Account' if you are new to XSEDE, or, if you have already created an account, click on 'Sign In'
Then, Follow the instructions.
https://portal.xsede.org/#/guest
https://portal.xsede.org/single-sign-on-hub