Uploading Images

I have installed WordPress and it seemed to be working ok. I wrote a post to see if it was fulling working and tried to upload an image to it. When I did it, in the bottom left hand corner it said “error on page” but never gave an error on the page. I have published the post, thinking the picture would show up, but it didn’t. It looks like the image isn’t attaching to the post.

Can anyone help? Thanks in advance!