how to setup sftp in virtualmin/webmin

I would like to configure sftp to work with existing users.

in file zilla i can configure public and private authentication keys using putty, however, apparently virtualmin is supposed to provide a means of doing this itself.

How do i use virtualmin to generate, and where is, the key stored for existing users? (not the key auto generated for new users…i read in another forum post that keys are found in .ssh (this doesnt exist in my user directory).

virtualmin really needs a user guide for each of its modules…considering ftp is a widely used function i dont understand why there isnt one for the proftp module.