Deviantart's member tutorials are dman helpful: For the record, I know this is a jump form my last sig, so I showed the layers in this animation. You can also see my avatar, which is watermarked to the right of Feraligatr (I love how awful the GIF quality has made it XD: SEIZURE WARNING!!!1 Spoiler
Wow, this looks great, next time you use a render, you should duplicate the layer, then make one with gaussian blur and put that one underneath the original, it makes it look way smoother.
Save as gif, and be sure to mark animation... On the sig, instead of blur like the one guy said(Seriously dont listen to him) try making everything but the render and bg invisible(mainly text) copy visible, paste as a new layer move it directly behind the render layer, and they mess around with the smudge tool on the edges of the render area, you want to make the render layer invisble, when your done mover your text up on top of it. This will take some time and practice, BTW.