After publishing your site, you can make changes to your galleries, pages and projects and then publish those changes by updating your live site.
To make changes to your portfolio after you have published your work, just hover over the projects, and look for the pencil icon. If you click on it, a drop down with three options will fall.
You will have the options to edit your cover image, edit the information for your project or edit the project content.
From the edit project content page, you can make changes to your project via the project editor and then when you are ready, you can click "Update Project." When you click back to your homepage, you can hit "Update Live Site" at the bottom of the page and your changes will push to your live site.