I use Imageshack
Just click on the file you want to upload via the "browse" button, then click "host it"
Then scroll down to the "Direct Image" copy and paste the link into your post.
You may find that the picture you want to upload is a biggie, because of the capabillity of todays camera's "Click on resize image" If you are using XP you can use Micro$oft powertoy image resizer. Then just right click the pic you want to upload and go resize. A duplicate will then appear, but of a smaller size.