The same way you add a standard image to an answer. Just find an animated image and add it normally. If you don't know how to add an image, it's fairly simple:
- Find the URL of the image you want. This means finding the URL of the image itself, giving it a link to a webpage will not work. Copy the URL once you've found it.
- Click the little button with a picture on it above the answer box. It's the sixth button across.
- A box will appear. Paste the URL and click "OK".
- A fairly simple code will appear in the post. Don't erase any of it, as it tells the program where to put the image and where to find it. The code will be replaced with the image when you post it.
Once you've done this, you should get the image you want. Example:
Just a quick note, don't put images like that as a signature in everything you post like Plasma Skitty did in that post. It's highly unnecessary and may cause the page to lag.