If the image file on your computer has a meaningless name like "12345.jpg", use the "Destination filename" box to write in a clear, descriptive title that will make it easy for viewers to know what the image depicts.
Use the "Summary" box to write a brief summary of what the image depicts and where you discovered it (if applicable).
Use the "Summary" box to add appropriate categories by using wiki markup (e.g. [[Category:Maps]]). See Category:Images for available image categories.
Click on the licensing box and select the appropriate license.