no root login after changing shell

[thomas may]

Hi,

i wanted to change the shell for user root to bash.
in the freebsd online handbook i found this command:

# echo "/usr/local/bin/bash" >> /etc/shells


but what i didnt know at this moment, that i have to install bash
before.
so i logged of as user root and get now on login the following error:

su: /usr/local/bin/bash: No such file or directory

can anybody please help me ...
thanx

- thomas