Anyone who held Bitcoin at the time Bitcoin Cash was created became owners of Bitcoin Cash. This means that Bitcoin holders as of block 478558 (August 1st, 2017 about 13:16 UTC) have the same amount of Bitcoin Cash as they had Bitcoin at that time. If your Bitcoins are stored by a third party such as an exchange, then you must inquire with them about your Bitcoin Cash.
Any transactions after the August 1st, 2017 ledger split are completely separate between Bitcoin and Bitcoin Cash. This means any Bitcoin acquired after the split does not include any Bitcoin Cash, and any Bitcoin Cash does not include any Bitcoin.