i know how to make the head spin on gimp, but how do you post it in a post spinning?

Once you've done all the filter stuff and created the frames you just save the image as a .gif.
Then open it in an image viewer that supports gif files and make sure it looks like what you're after.
Then simply upload the .gif image to an image upload site such as imgur.
Then just post it to the forum.

Thanks that was the information i was looking for.