vim mapping a function key to open a specific file and in the same time , G go to the last line of the file

i use vim.
i have a journal file that i use everyday and constantly on and off. i decided to map a function key to it.
how to Code::e journal.txt G?
what i want to achieve is map this function key F6 to open this journal file, and go to the last line "G" . but vimrc prompt error.

need help

thx