Would really appreciate help. Checked out another thread but could not understand how to resolve this issue. I need step by step

I formatted my hard drive to Apple to help daughter move files off her computer onto PC and of course it did not work. The drive did not show up on her new netbook or my PC.
How can I reformat, or even find it to reformat, so appears again in My Computer and is functional please?
I did find my way to disk management at one point and now forget how I got there. I could not see the drive in there at the time but not quite sure what I was looking at anyway.
Thanks for any tips and need a bit of step by step if you would please.
x