Formal Letter How Should I Start A Formal Letter?

How should I start a formal letter? - formal letter

I want a letter to my employer for hiring me (in English, thank not my mother tongue). Can someone please tell me:
1) Is it correct to write to Dear ... in a formal letter?
2) How do I create my letter if I do not want to do with a particular person, but to a society?
I would be glad to answer a English speaker who has some experience in writing formal letters. Thank you very much.