By default, your friends already follow you on Facebook. Sometimes, someone want to follow you but their can't see any Follow button. You can turn on or turn off Follow button if you want. I will show you how to do that, this is really easy. Please, seeing my introduction below:
Step 1, click here and login Facebook:
Step 2, click here and edit your follower settings:
Step 3, click Friends and chose Everybody
Done.