When you post a question in the forum, its always good to make sure that you actually tell us what module or modules you are using. I am going to assume that you are using
Net::FTP.
That said, if you look at that documentation in the link (which is the cpan page for the module), you will find there is a "cwd()" function that will change the working directory.
Also, please put code tags around any questions you ask in the forums. It is required. I have done this for you this time.
Regards,
Jeff