RSiteSearch("change directory")  will take you to an
archive site that should help. 
or type
?setwd  to get the relevant man page.  
--- Georg Ehret <georgehret at gmail.com> wrote:
> Dear Ms. R,
>    I struggle with a very basic command for most of
> you: How to change the
> working-directory by command-line?
> 
> Thank you!
> Georg.