Welcome to the forum.
If you want to insert an image into a post, you're going to need to upload the image to an online image host (e.g. Photobucket, Flickr, private web space, etc.) and use a link to that location. An image sitting on your hard drive isn't going to be found by any other system
You're also better off editing a post to try to make a change, rather than creating a whole new post to try the change. There's also a "Preview" button next to the "Submit" button that will let you see if you've succeeded without actually uploading the post to the forum. It may come in handy.
(I've cleaned up your extra posts as well)