The Trick:
Facebook doesn’t allow users to upload animated GIFs anywhere on the site, so if you wanted to have an animated GIF somewhere, you’re out of luck, unless…
There is a trick that allows anyone, who has the following resources, to bypass this limitation in uploading animated GIFs for custom tabs.
1) You must have Adobe Photoshop C5 & Quicktime Player.
2) Select the animate GIF you want to upload.
3) Open Adobe Photoshop CS5 and go to File > Import > Video frames to layers. In the File Name box, just enter *.* as your filename and choose your GIF image.
4) Resize your GIF to 111 x 74 pixels to fit the custom tab image .
5) Save your file in a PSD format. Check the save option, ‘LAYERS’