basic 7 need help!

Ok i've read so many articles etc on this and i can't seem to get it. javascript:void(document.cookie="username={binary encrypted text}"); Which i have encrypted off a website of the username sam.

Now when i go to use this injection i put it in the address bar like this http://www.hellboundhackers.org/challenges/basic7/check-cookie.php?username=javascript:void(document.cookie="username={binary encrypted text}");

and it doesn't work auth failed?? what am i doing wrong please help!

Maybe you're doing the javascript injection wrong. You are pretty close. Try to learn how javascript injections work. I recomend Google :D. Try to search javascript injections at the greatest search engine :D