I see the option to upload and select colors from the image here
There is an option to go to this page from the Create section.
After you select the colors, the Title, Tags and Save button to the right of the image allow you to name the theme and save it. You have to be signed in with your Adobe ID at the time.
I've just noticed this from the Kuler team's thoughts on the redesign:
Create a theme from an image: We know many users really like the “Create from an Image” feature. Unfortunately, this feature was not ready for the new site launch. So, rather than launching a buggy or half-baked feature, we decided to take a bit more time to get it right.
We intend to add this feature to the site as soon as it’s ready. Until then, you can use the free iPhone app to create themes from images.
So, it looks like that feature is coming back soon.