First you need to create an account ( if you use on you mobile, you need to download the app) , log in and follow the topic and the people that you want to recieve information from them. You can also post what you like and share with them
i use these 2 way
1. Turn on fuction that will alert you when you fb account is logged in by another phone
2. Use Security function, when you log in from another device, FB will send you a security code to your phone and you can only get in when you get the right code