When you're posting a comment, you have all sorts of lovely HTML features you can use for you post. One of them is called 'Attach image' (fifth from the right), click it and you can either upload a .gif from your computer, or copy the image address of the picture into the box that says 'Image URL'. That's it, really.You can also Toggle HTML View (farthest on the right), and if you want, you can memorise the HTML code for next time - but attaching is definitely the easy way to do it.
@Belewyn Oh yeah, how do you get a signature?
@NightshadeRaven How do some of you have a signature then?Do you just like write your signature each time you post something?