You are evidently using a web site to send e-mail. You don't tell us which one. What you are describing is not the standard way such dialogs work. I assume that after you press the add attachment button, a dialog comes up. If so, shift tab once or if necessary twice. You will be in a list of folders and files as you are in My Computer. Move back through the list with the back space. Move forward by pressing enter on something such as a folder. Find the file you want and press enter.
I've almost never added an attachment using a web site but that should be all you have to do. As I said, I've almost never done this but I believe that you will have to allow time for the attachment to upload, if it is at all large. I haven't done this enough to know if you are notified on the page when the attachment has finished uploading.
I'm able to use NVDA to send emails, but when I need to attach something, I need help, because I don't know how to navigate the 'upload a file' window using the keyboard. What I need to do is:
- Navigate to the address bar so I can type in the folder address, such as C:\downloads
- Navigate back to the list of files so I can search for the right file and select it for upload.
Can anyone please tell me how I can do this?