Server wordpress permissions

please be gentle as my server knowledge is next to none!

I've been asked to make some CSS changes to a wordpress site - fine, I'm good at that! I have all the ftp inf开发者_如何学编程o and the wordpress passwords, but as I edit files and try and re-upload them using Dream Weaver I get an error that I don't have permission to write to the particular file. So, the first thing I thought to do is right click the file and edit permissions, but as I try and do this I get the same problem of:

An FTP error occurred - cannot put the_file.js.  Access denied.  
The file may not exist, or there could be a permission problem.   
Make sure you have proper authorization on the server and the server is properly configured.

File activity incomplete. 1 file(s) or folder(s) were not completed.

Files with errors: 1

So, my question is - by knowing the ftp details is there any way I can change the permissions, or is it something to do with server configuration that I have no control over? Many thanks

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This means that the FTP username you were provided does not have permission to modify files. YOu won't be able to reset the permissions either. You should contact the server admin and have them grant your user account the appropriate permissions to modify files.