how can i see my hard drive letters

Hello,

If by "letters" you mean something like C: or D: ...etc , you have to know that Linux does not recognize hard drives and/or partitions same way as Windows.

For instance,

open a terminal (usually CTRL+ALT+T) and issue this command

    sudo fdisk -l

it will ask for your password, write it carefully, because nothing will show up (like no writing). There you will see a list of all your Hard Drives and partitions.

Graphical, when you open nautilus (or Files) at the left you will see a list under devices, usually as 40GB filesystem.. etc (of course GBs here are an example). There are the partitions of your Hard Drives.

Also you can set labels if you want , labels like : data, windows, files, common.. anything you like. You can do this from "Disk Utility". Search and open disk utility and carefully click the Hard Drive you want, click the partition you want and then search for the option "Edit Fileysytem Label". The partition you will change the label must be unmounted. If you cannot unmount it, then you should do the process from a Live Media (DVD/USB) of Ubuntu.

Regards
 NikTh