Hi !
You can use imgur.com to upload your pics to the internet. Then, right click on your newly posted pic -> copy image address.
Last step is to paste this address between the [img][/img]
brackets. You might want to put your pic in a spoiler if it's really big or there are too many of them to post.
[spoiler][img]PictureAddress[/img][/spoiler]
Hope that helped, have a nice day ! =)
Rose