You must first be logged into your site.
Create an album if one is not already created.
There should be an "Upload Image" button when you hover over the album name. You can upload a single image in the advanced editor by selecting the image from your computer with the "Browse" button at the bottom, and clicking the "Upload" button.
Once within the album, click on either the "Upload Image" or "Bulk Upload" buttons that appear below the album title to upload a single image or multiple images.
Clicking the "Bulk Upload" button launches a Java applet that allows you to "Browse" for files on your machine and upload them all to the website. After the images are uploaded, you can add Titles, etc. and reorder them while logged into your site.
Hope this helps!