The address and date should me written in right hand corner.after writing the address and leave one line and write date. the most common salutation in an informal letter is dear...
dear mimi ,
introduction : write paragraph summary on your topic.
the body : write 2 or 4 paragraph consist your msg detail.
conclusion : write conclusion what your main idea in your letter.
your informal letter should be end with best wishes love etc... and that should followed by comma.