You can upload to photobucket if you want and just copy the IMG code over and paste it.

or

Upload to "my album", right-click, copy image location, click the insert image icon, paste url. Either check host locally or not.

I have found that usually uploading them to photobucket or the album works better than uploading from your computer directly.
I've had a few issues myself still working on what is best. I am hoping to write a FAQ on how to post pics etc. in the next few days.