I use a variety of methods to clean fretboards. This one is the best I know of for a dirty fret board. First take your strings off and use a guitar pick or your fingernail(covered with a cloth) to rub on the fret board. The pick will scrape some off....
I have a guitar and I am really new at it. I want to put a strap on it but where does it go? How do you put it on?
Acoustic guitars usually come with a strap button at the butt end of the guitar but not at the other end, so the other end of the strap needs to be tied with something strong like a leather shoelace to the neck, under the strings, behind the white nut. I know some manufacturers that doesn't even put one at the butt end of the guitar on some models. In that case, I would advise having one professionally installed.