Dumb question: How do I open an image

[Ofnuts]

Strange ways.... if you are in the explorer, your can right click the image and open in with Gimp, not need to open a file selector in Gimp. If you can't do this, then you just need a bit of set-up (aka "file associations").

Otherwise, see if there is a pencil icon to the left of the directory "breadcrumbs" at the top of the dialog. If so, click it and you can then enter a path directly (you can also type in the path, the input field supports "tab-completion").