The permissions area is where you'll decide who gets to see or edit your ePortfolio. "Private to me" makes it only viewable to you unless additional permissions are added for select users, courses, or groups. "Private within Your School" makes your ePortfolio visible to everyone with access to Digication at your school, and "Public" makes your ePortfolio available to the world and searchable by Google. Simply select the access you feel most comfortable with (you can always edit it later), unless you've been given specific instructions to share your ePortfolio with a professor or course, in which case you'll want to click on "Custom Permissions."
If you've been instructed by your professor to share your ePortfolio with a specific user, group, or course, then this is where you're going to do so. Simply search for the individual or group, and they will display in a drop-down where you can click on them and they'll be granted viewing access to the ePortfolio.