See the FAQ here: http://www.wrongplanet.net/postp2584318.html#2584318
Basically you need to have the image stored on an external site, then you'd post a link to it here.
I use Photobucket - similar to Flickr or ImageShack - most (all?) of them offer a free image hosting service too. The free accounts will restrict the number and size of images you can store, but the paid accounts are still pretty cheap and will allow many more files.
Your WP profile can only have one picture attached - the avatar, and that's restricted to small image no larger than 130 pixels wide by 160 pixels high, with a file size no more than 15.77 kB.
You can upload a suitable file through your profile editor, accessible via the "My Account" link at the top of the page.
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Giraffe: a ruminant with a view.