What is a good site to link an image with?

For a drawing competition I'm entering, I am required to link an image I have made in one of the submission boxes. What would be the best standard site and way to do this? I haven't used image sites a lot in the past so I'm uncertain.

My worry is that it could be one of those image links that disappear or time out and are automatically deleted after a while (in which case they don't get my submission). I just need to know that the image link I post will stay there for at least a few months (but preferably forever, I'm not sure if I'd need an account for this). It'd also help if they trusted the link from first sight so they'll click it.

Help appreciated!