The moment you are in the game and after solving most puzzles and watching clues this will happen. The game is telling you that you have a new clue to read, to read the clue left click at the top of the screen in the black border area, this will take you to a new screen and you can read the clue. The clue screen shows a qwerty keypad at the bottom, left click on the close button after reading the clue to return to the game.
Also on the clue screen you can click on the right arrow for more clues. The clues usually relate to a place or object to find, the clues are also usually cryptic and sometimes contain anagrams.
I find the clues don't help that much, so basically just go everywhere click on everything!
Hope that helps.