I usually google. for instance, if you want a "hello" gif - google hello gif, and you get a load of gif images, simply click on the image, click "view image" then copy the image url from the address bar and when you click on the post image in reply - paste the image url into the box and hit insert. you'll get:-
when you get a load of images, go through each one until it moves with the words you want, then it's a gif. anymore problems, I'll try and catch up later, back to painting my kitchen, I've had my break.