Whose" is a possessive form meaning "of whom" or "belonging to who" and is used in the following way:
Whose books are these?
The men, whose lives were ruined, claimed compensation from the government.
I do not know whose shoes smell worst.
If you are in any doubt, consider whether the who's/whose you are using can be replaced by who is or who has. If it can, then you need "who is", if not you will need "whose".
