You do not want to Raid an ssd and hdd. Assuming you want the OS on the ssd do this. Plug in only the ssd. Go to the bios and made sure it is in ahci mode. Save and exit the bios then install windows. Now you can turn off you computer and hook up the hdd then initialize the hdd in disc management.
So plug in the SSD, go into Bios change it to achi mode. Than install windows to it, once every thing has been set-up than I can connect my HDD to store stuff on ect..