Please read:
https://winscp.net/eng/docs/library_example_keep_local_directory_up_to_date

If that does not help, come back.

Apologies for my ignorance, I'm sure there is a simple answer to this.
I understand the synchronisation command, but, how can I keep local folders in sync with a remote ftp directory, ie. when the remote site is updated, new files are automatically downloaded and updated in my local folders without me needing to instruct scp to resynchronise?
Thanks for any advice
gph