Cannot upload images

I came close to getting an answer on the forum; however, I do not have the plugin that the forum discusses. Also, the forum was closed to any new comments.

Each time I try to upload an image, I get the message “Firefox can’t establish a connection to the server at localhost.” I tried to do it with IE; however, the same message appeared. I have tried using both templates – Twenty Eleven and Twenty Twelve. Please help. I can’t launch the blog until I can get my header in and everything in place. Thank you for your assistance.