How to use extra partitions created through the linode dashboard

I have created a 20g root and 2b swap (might drop the root down to smaller size, but 20 is fine for now). I have created another 'disk' within the dashboard (8gb), and wanted to mount this under /usr/local

I looked at /etc/fstab to see what the partition names are for the others. They were /dev/xvda and /dev/xvdb (makes sense). But in /dev, I see no /dev/xvdc. Now in the dashboard, I went snooping around a bit, and under the 'rescue' menu, I do see my 'disk' listed as being /dev/xvdc I have also rebooted the VM just in case it needed booting after the disk was created. Still no go.

I can handle mounting the thing, and getting into /etc/fstab so it is always there, IF I could figure out where the heck the device is.

Can anyone point me to the obvious answer to this riddle. I know it is something I am doing wrong, or have not done yet, but i simply am not sure what.

TIA. Jim.