Help how do i attach a word doc or a PDF file to a post?

You know when you say you will do something and it turns out to be a complete ball ache well this is what happened when i said i would do my first ever tutorial about the beachbag i made!!  The bag took less than an hour to make the tutorial somewhat longer and now i can't work out how to put a PDF or word document into a post arrrgh!!.  Can anyone help me i'm clearly technically challenged.  So i'm hoping that one of my lovely followers knows more about blogging than me (that can't be hard!) and can tell me how i do it! anyone?