Content on Portfolio is organized into Pages.
To add content to Portfolio site, you will need to use/create Pages. Pages can be used to upload and showcase your work or to create an About page.
How to Add Content
To add either a Project or Custom Page, click the "+" icon on the left hand column of your Portfolio editor. Then, use the tools to add whatever type of content you'd like.
You can also click the "+" icon in the lower right of your Manage Content menu:
Use the file picker to select images from your computer, or click the "Creative Cloud" icon to import them from your CC files. Note that you can also embed content from other services, add text, and much more.
Once you've added your content, use the customization tools to adjust the look and feel of your content.