See the UNIX Programmers Manual or via % man csh
% cd /usr/smith/bin
specifies that the working directory will be /usr/smith/bin
% cd junk
specifies that the working directory will become 'junk'
(which is in the current directory; if the current
directory is '/usr/smith/bin', then after this command, the
current directory will be '/usr/smith/bin/junk').
% cd ..
will 'back up' one step from the current working directory, i.e. if you
are in directory /vb/you/yours/stuff, a cd .. will position you at
/vb/you/yours.