You need to have your .gif somewhere on the internet and then just copy the url location and have [img]location with [/img] at the end of it and it should work. As you can see from the photo gallery, some of us have the .gifs there and then they work from having them on the internet here. Give it a try and hopefully it will work.
Also if you wanted the .gif in your signature, you'll need to go into profile and in the space for "signature" do the same thing with the .gif you want to use for every post, that also should work, let me know.
Mary Lou Scanlon
NCL Pride of America April 24, 2010
NCL Epic February 12, 2011
RCCL Allure of the Seas - September 18, 2011
Celebrity Eclipse - February 11, 2012:
RCCL Navigator OTS - February 9, 2013