Once you have a published site, you can make changes to your Galleries and Pages and then apply those changes to your live site by clicking "Update Live Site" on your Remote.
To make changes to your Pages after you have published your work, just hover over the cover image, and look for the pencil icon. If you click on it, a drop down with four options will fall.
You will have the options to customize your Gallery's theme options, edit your cover image, edit the information for your Page or its content.
Saved Pages will not automatically update to your Live Site. In order to publish any changes, click on the green "Update Live Site" in the remote.