There are multiple ways to quickly find an image if you want to change the metadata on it or upload a slightly different version (color-corrected or slightly cropped). Remember, if you want to drastically change an image, create a new image node.
Note: Because of how images were handled in BornFree, all imported images on the new Grinnell.edu have names like index4_84.jpg. One of the first things you can do to improve your site (and make it easier for you to maintain), is to go to the image nodes that are referenced on any of your content and give them a better title and good metadata.
There are two easy ways to find an image node.
The "Images" tab
When you first log in, you should now see a new "Images" tab along with "View," "Edit," and "My Sections."
Clicking on this tab brings up an interface allowing you to search for images and help you find them.
Finding a Node
Because Images are nodes just like pages, events, etc., you can use the node search to find images.
Find an image Node ID (aka nid)
If you know what page displays a certain image node, you can quickly find the image node from there.
Just use either of the image autocomplete fields (Large Image or Small Image or either Browse as shown in the Figure) to find the image you want. Once the image you want is selected (or if it was selected already), find the digits in the node id (e.g. 12345 from "[nid:12345]") and go to grinnell.edu/node/12345 (or whatever your node id is). You can now see the image you want to edit.
This same strategy works with Files using the Attachment field.