Image appearing for me, but not other users.

I have inserted an image for one of my posts.
https://www.snoopyscorner.com
It is the second post down. I see the image just fine when I view the page, but others only see the red “x”
Here is the code for that post.
<img src=”////wp-content/uploads/2007/03/dogjoke.jpg” />
Am I doing something wrong?
I was in the admin area making a post and uploaded the image and then pasted the code in the body of the post.