Adding new device (without having the device)

Hey there. I know I saw how to do this before but of course .... forgot.

I am wanting to add a new device to be "recognized" by calibre but I don't have the device handy (with my daughter).

She handed me a thumb drive with four books on it and I can't get them into calibre to store or convert them.

I have peeked around where I thought it was but .... couldn't find it.

Any help for this semi-computer literate person would be greatly appreciated!!!

Thanks in advance~~:o