I saw your pic when the link took me to the flickr page, nice dog shot. Its truly a great b/w and the white background really isolates the subject. Great look in the eyes.
Now for posting images, since you're posting from flickr its rather easy. Just open the photo on your flickr page, then above it click the button "Share This" and select "Grab the HTML/BBCode", then choose a size and select "BBCode" underneath the box. Then just copy the entire contents of the code in that box, and past it onto a forum.
On standard html pages (not forums), just use the html block of code.