Nicola,
It would appear that the link you are posting is the image you are trying to post.
If you just want to post a link to your gallery then you need to grab the url from the image gallery, not a specific image. Like so:
Nicola's Gallery.
To post a picture from your gallery, you need the url of the image. At the moment this can be found by right clicking on the magnifying glass near your picture and clicking copy image location. Then when you click on the postcard icon above this is the url you will need for the image to appear.
For your signature, in the blank box you need to type whatever it is you want to appear as your signature. For instance "Visit my gallery, here" or whatever you want this to be.
Thanks,
Amy