I need to enable ftp access on some web directories in apache. What is the best way to do this?

My apache server is running on linux. It runs as user wwwrun and group www.
What should be the permissions and who should be the owner of the web directories and files?

What I need to do is to enable ftp administration of one of these web directories. It contains one free Customer Relationship Management web application. It stores data in mysql. It has lots of directories and files. To tell the truth I do not know much this application. This application is managed by one third party group.
I tell them that I make ftp access to the complete directory and asked them to set the right permissions on each file.

My ftp (pureftpd) server runs as ftpuser and ftpgroup. When the ftp client connects it cannot make any changes in files because the ftpuser do not have any permissions.
What is the best way to allow ftp admin on it?