I have spoken about this process in the past, but in light of the recent Equifax breach, this advice is once again both timely and sound. Here are a couple of great links to help you better understand the process.
https://krebsonsecurity.com/2015/06/how-i-learned-to-stop-worrying-and-embrace-the-security-freeze/
https://www.consumer.ftc.gov/articles/0497-credit-freeze-faqs
Virtual Sweater Vest 