as for setting up the raid, while in the bios, set the ports the hdd's are on to raid; save and exit. Since you already have windows installed you may need to move the drives to a different controller than the one your ssd is on otherwise windows won't boot since changing to raid changes the driver needed. The controller the ssd is one should be set to AHCI.
While the pc is booting, you'll be prompted to press a key combo to enter the raid setup. ctrl-i or ctrl-f... once in the raid setup select the option to create a new raid. set the type to 1, add the hdd's, use the default values for the various settings, name the array, and then format it. Reboot when done and windows may want you to install the drivers when it boots up so have the latest ones ready.