Post #5 makes me think you will have your work cut out for you. If you know about a web site's source code, that might give you a clue for what you will need for the explorer object method. Search for "excel getelementsbyid" to find examples that use source code elements. Chrome makes looking at a site's source code elements easy. This search show some code that may help as well. "excel explorer submit button"
Attached is a simple example using the API method that I explained. In it, notice that I had to know that the file extension was gif. Normally, one would know such.