alright i have read up on java script editing on a website provided to me by SpOonWiZaRd
(Thanks again man)
but i read up on the script:
javascript: void(document.cookie="PHPSESSID=Hacked"); alert(document.cookie)

the site said it is suppose to change the cookie but it just creates a new one at the end of the list. is there something i am doin wrong in this script.

i do know that you are suppose to put the first part of the cookie where it say "PHPSESSID" but i did that and it still placed a new cookie at the end of the list..
can someone tell me what i am doing wrong