how Facebook help us to find more customers?

Having no clue whatsoever about your business, I can only speculate.

I can tell you that Facebook mainly helps companies where the target consumer is somewhat similar, demographically speaking, to the target/standard FB user. E. g. if you are marketing to seniors (say, you're selling retirement time shares), there's more of a disconnect and FB is unlikely to help.

FB can be helpful in order to provide a platform for customers to speak their minds, but be aware that that can get ugly very, very quickly. Company engagement and message need to be carefully monitored. You can't just slap together something and expect that it will be great.

Look at the Onion as an example of an organization that screwed up big time recently but has garnered some good will be apologizing and promising to do better (it remains to be seen if they do). Want to know about someone who manages Facebook effortlessly? Look no further than George Takei.