JS4!!!

i read the article on this one but i still dont get it. what do i need to do the the use+this part from what i read on the other posts on js4 its got somthing to do with crafting my code or somthing. my brain is racked from thinking where do i go? from here

click "use this" and see how the url changes. –DON'T READ THIS IF YOU WANT TO DO THE WHOLE MISSION BY YOURSELF– you're going to use an xss (cross-site scripting) injection into the url bar to alert your cookie. however you will need to do it like you would in a page, so use the <script> tags, that part got me for a while. hope i didn't give too much information away.

Ahh dang it that was simple why, grr why didnt i see it why didnt it come to me in the begining thxxtrmsk8r91 that helped lots ^^