Hello .. I will give you some help in writing your letter ..
I'm going to tell you how to write a very formal letter..
You should write your address right aligned in the top of the page..
after you finish writing your address skip one line and write the date also right aligned on the page..
next you should skip 1 line and then write the sendee's address .. in other words the person who you want to send to..
after that skip 1 line and write your greetin with no indention .. and since you dont know who you are senting to just write " Dear sir or madam, (dont forget the comma)
then skip another line and start writing your paragraphs .. and there is no indention too .. dont forget to skip 1 line between each paragraph..
when you finish writing your paragraphs skip 1 line and write " Yours sincerely, " or " Yours faithfully " .. but dont write something not formal .. like best wishes or other stuff ..
then skip 1 line and write your name..
dont forget that there should be left and write margins and there are no indentions through out the letter ...