You should have receive you're droplets password for ssh after creating it. But if you can't find it make sure to look in your spam folder.

With you're FTP client as host you can use: sftp://serverip to login to your droplet file system.

Have you selected an SSH key while creating your droplet?

You may first set up all your server settings. Have you already installed an ftp server? There are articles on the commynity page explaining how to do so.

https://www.digitalocean.com/community/articles/how-to-set-up-vsftpd-on-ubuntu-12-04