Do you want to post a picture in the galleries or in a message? For the galleries, see the left side of this page and click on the appropriate link. Then follow instructions. For posting in a message, fill in the complete URL information in the "Optional Image URL" block that shows up below the comments block where you write your message.
Of course you will need to have the picture in digital jpg format located on your hard drive to upload to the galleries. For the message picture, the image must be located either in the galleries on some other internet server that is not blocked by this site due to competitive sale of tractor parts.