Please don't use mobile phone abbreviations! It's "your", not "ur" in English.
There are many variations of letter. Here are three common ones:
Formal: Start with Dear Sir (or Madam); end with Yours faithfully, (bottom left).
Business: Dear Mr Smith; Yours sincerely,
Casual: Dear Jenny; Kind (or Best) regards, (or Yours truly,)
If you don't know the name, it's safer to be formal. If you don't know your neighbours name, why not go and introduce yourself before writing a letter? How can you be writing to your friend, manager or penfriend but not know their name?