Ok, so you first find an image or gif somewhere online, then you right-click it and select "copy image address" or something like that. Then switch back to ALL page and click New Reply.
Type what you want, then click the small box that has a mountain with a sun over it. just to the right of the bullet points. then paste the address you copied from the other page.
And thats it, if you need more help let me know. I will help you figure it out. You can Pm me if you have questions, I can send pics if necessary.