To signup for Adobe Portfolio and begin creating your personal website, visit www.myportfolio.com, and click the "Get Started" button.
From there, look through the available layouts and select "use this layout" next to the one you'd like to begin with (note that you can change layouts at any time later on).
Then, either Sign In with an existing Adobe ID, or click "Create an Adobe ID" to create one.
From there, you're in! Enjoy creating your personal website using Adobe Portfolio.