git config git-ftp.user 'FTPUserName'
git config git-ftp.url ftp.example.net/public_html/optional1 /optional2
NOTE: It is interesting to inform the root folder of your server, ex: public_html. You can enter as many subdirectories as you want:
/optional1
/optional2
git config git-ftp.password 'yourFTPPassword'
git ftp init