I use ImageShack to host, you don't even need to sign up!
http://imageshack.us/
...then just go and see the photo(s) you just uploaded
(click 'full view') and right-mouse click "copy image location"
then come to the forum and right-mouse click "paste"
between [img] brackets and you are done

You can upload dozens of images at one and imageshack
has also a handy "copy code for forums" function that
copies and pastes all uploaded pics simultaneously.