Welcome to LQ!
Where are you stuck exactly? Sounds like you have booted a USB "LiveCD" of some kind?
If you only have the one drive on the host (desktop) use sda for grub-install.
If you have more than 1 drive,
say so
Lots of hits on <search_engine> for
Code:
how to install simplicity linux
Youtube has videos.
Try sda and let us know.