Hello and welcome to PC Help Forum.
Well you buy 1 double IDE lead wich will connect 2 IDE hard drives internaly.It is one grey flat lead with 3 connections on it.One for MB and the other two for HDDs.Do you have enough power connections to power the HDDs?You can buy power supply splitters.
You would have to set little plastic jumpers on IDE HDDs to slave.
If you want more information on how to fit a slave drive we will help you.
