Help with basic 9 please :( (possible spoiler)

i managed to get into the login.php section but and i use a poison NULL byte to gain access to the source but it just says it cant find it, ive added it to every text box and every url that relates to basic 9

im thinking bout pulling whats left of my hair out as i have no clue what to do :(

i think maybe theres an error because no matter what i try i cant seem to do it, basic 8 was hard enough :( ill keep trying but it doesnt seem to work

Would it work if i put the whole url in the text box followed by the poison null byte or would it have to go in the url (sorry if this is a spoiler)