How to format and link my disks?

ok, my disk failed in the readynas so i removed the 1tb disk out of my sky+ box. I've now installed this disk into the readynas hoping it would automatically format it and get up and running, it didn't.
on starting raidar it has no option to go to frontview (setup button is shaded grey) and it says disks are not present under the disks column and bad disks detected on end column .on the duo the power button flashes, green led flashes very quick.
have i done something wrong? what should i be doing? any help appreciated.

i swear this duo is causing bad disks, ages ago i bought a new 2tb hard drive and installed it, bad disk. admittedly it was from a shady website so i didn't do anything about it. now the readynas says the disk i bought around 2 years ago is now bad. now i've put in another disk, bad disk. it was fine 10 minutes earlier in the sky box??? I've had nothing but headache with this thing, is it just my duo that is sh** or are all netgear products rubbish?