Is the pic you're trying to load on your computer? If so, go to the "Add an Attachment" section that appears lower on the page where you "Post a reply", click the "Browse..." button and select the file that's your coat pic. In the "File Comment" box you can give the name of the pattern or whatever you want to say, then click the "Add Attachment" button. After you're finished, click the "Submit" button.
If the pic is in a book you'll need to scan it to get it in your computer for attaching. Be careful not to include the pattern itself as this is probably copyrighted and we don't want you to get in trouble!
If the pic is somewhere on the internet you can create a link to it. The easiest way to do that is to copy (control, c) the site address (known as a URL) that appears near the top of your browser and the paste it into your messages (control, v). This way anyone who wants to help you can click on the URL and see the pic.
Hope this helps.