Let me show you an example.
First you get the link of the photo you want , by right clicking on the photo and copying the link , alternatively , if the pic is saved on your computer , upload the image to an image uploading site , such as
imgur.com.
So i have this link currently saved to my clipboard
http://images2.fanpop.com/images/pho...29-800-600.jpg
What you'll want to do is put the Tag around the link so it's be [.img]http://images2.fanpop.com/images/photos/3000000/Homer-Simpson-homer-simpson-3065329-800-600.jpg[/img]
I put the dot in on the first [IMG] so I could show you .
When you do it , don't add the dot , obviously.
Having done that this is what should appear
when you upload your post.
Capitalizing the img tag isn't necessary.
You can do it to as many images and Gifs as you like.