Nama

Hello,
Namaskar friends
Iwant to learn Computer Hard ware, i want to assemble format and any latest devices in the marketor sostware install and enjoy it plz give some valuble information
then
i have two harddisks in my system i can not connect together making one master and another slave because while in net connecting it spoils the slave hard disk so
where i have to make a switch to the power supply cord
is this switch available in the market if so what its name plz..tnaq.....