Hi agentPPPP
I am assuming you are using the dead laptops 2.5" drive and wish to hook it up in a desktop as a primary drive ?
if this is the case you will need a sata data cable plugged into your motherboard and into the drive and a sata power connector from your psu plugged into the drive.
you can get a 3.5 to 2.5 drive bay adapter to put the drive in to hold it in your 3.5 bay. then once all hooked up , install your operating system