Redhead_roleplays said
It will pop up like yours does?
It should, once you enter the correct URL. The reason why your signature image is currently broken is because you copied a website URL, not an image URL. An image URL is not a URL for a page that happens to contain an image. It is the URL that you get from right-clicking the image and selecting "copy image URL",
or the URL you get when you have a tab containing
only an image (like when you're on Google Images and you click "view image", and you see the image by itself). You can get the image by itself on other sites if you right-click the image and select "open image in new tab". Generally image URL's end with an image file extension (like ".jpg" or ".png", etc), which is a good way to check that you did it right.
Anywho, once you have
that URL, put that into the code and it should work.
And how about profile pics ?
For those, you can't copy a URL. You have to upload an image from your computer, so make sure that whatever image you want to use is saved there.
Also, avatars tend to lag quite a bit, so you might not see yours right away. Be patient; it should show up after a while.