ViperBob, Welcome to the forum.
Adding attachments is fairly straight forward. Click on "Attachments and other options" below the text box, then click on "Browse" below the "Attach" heading. Find the file on your system that you want to attach and click on it. There is a limit of four attachments and there are file size restrictions. To preview, click on the "Preview" button at the lower right. The preview screen appears above the screen you are typing in so you must scroll up to see it. The preview screen includes your text but will not show your attachments. Experiment a bit!
Your car looks great, we would love to hear about it and see more pictures.
Again, welcome!