Use the attachment bar under post icons, use browse then "Add This Attachment".
After that, files that you attached to that post will appear under attachment bar. Clink in the post where you want the image to be placed and then click "add into post" by the right image.
Note: This has no image limit, but it uses your attachment space and you will need to clean it up from time to time.
Or
Use
http://imageshack.us/ you can register if you want to have access to your uploaded images later or just upload without registration if you don't care. Then use
CODE
[Img]Direct link to image[/img]
Put in the direct link to image that ImageShack gives you.
Note: If I remember correctly, it was 12 images per post.