I worked it all out eventually

thanks! If there is anyone else who is a total dunce like me, this is how I did it (everyone else can feel free to roll their eyes and say 'Well, DUH!')
- Go waywayway back to the emails I received from my host. One of these contained a seperate password that I would need to use FTP.
- I used FileZilla for this, but my host has it's own FTP as well. Not sure if all hosts do. FileZilla is nice and easy though.
- Logged in using the address they gave me to login to, and that password.
- Found the WP files my host has.
- Opened my own WP files.
- Drop and drag addons from one side to the other!