I assume that you are running XP ?
If so go into Control Panel/Admin tools/Computer Management/Disk Management.
That should show your existing hard drive as C and presumably your Floppy and CD/DVD drives as B and D and E.
It will also show your new slave drive as no drive letter and unallocated, I think it wil be called Disk 1.
If you right click in the part where it shows Unallocated you will get the option to initialise the drive.
Just select the options that you want as they come up, ie basic drive, primary partition, quick format etc.
If the drive letters are as I assumed earlier it will assign it as F, you can change it at the stage where it says it will be F if you wish.
I have been changing slave drives to S for most people lately so they know to use it as storage so that C can be wiped if necessary without losing saved data.
Hope this helps, if it doesnt sort it get back to us