Depending on what system you're using, select the image URL by clicking one these: Chrome: Copy image URL. Safari: Copy image address. Internet Explorer: Properties > Copy the URL address shown.
The difference is that you are using INTERNET EXPLORER, and I am using GOOGLE CHROME as a Web Browser. With your web browser, you need to choose PROPERTIES. That will produce a PROPERTIES box as seen on the left. About half way down in the PROPERTIES box you will see a line labeled Address (URL). Use your mouse to highlight the URL address. Then Right-Click the highlighted text and select COPY. Then go back to your Corvair Forum editor and Paste that text between the IMG markers, as shown in the illustration below...
Left click (twice) for full enlargement... I know it is a little more complicated than the Google Chrome method, but once you've done it a few times it will seem easy. Note that the Corvair Forum Image (IMG) tool is circled in red on my illustration.