After you have created a Pantheon account, log into your Dashboard and click Create your first site.
Enter a name and URL, then click Create Site. The only valid characters are letters, numbers and dashes.
You will then have a short wait while Pantheon creates and allocates the resources for your site's environments.
You now have several options. Select Install WordPress, which gives you a blank site with the code pulled from a Pantheon maintained fork of the project.
Pantheon will now build your site environments and prepare your WordPress site. When complete, just click the button to visit your Pantheon Dashboard.
Congratulations! Your Pantheon site environments have been configured. From the Dashboard, you can control your site's settings, manage team members, perform workflow operations, and a lot more.
You will eventually have three environments (Dev, Test, and Live), each with a separate version of your website, but you need to finish development site installation first. Click Visit Development Site at the top left of your Dashboard to launch the site.
Now you will add site information such as administrator username, password, and email address. Click Continue when done, and the installation will complete. On the login page, enter the username and password you set when configuring the site.
You are ready to start development! Click the Visit Development Site button to view your Dev site at anytime.