To complete the puzzle, use the mouse to click left for a black square, right for a dot. Click again to clear any mistakes (but you won't make any, will you?). You can also click and drag to fill in a row or column with either squares or dots. As you complete each row and column, green or red indicators will light up to let you know whether it matches the clue or not. A green light doesn't necessarily mean it's correct, but it does mean that the number of squares is right. To make the display bigger, press the "Float window" button and resize the popup window.
Given up? If you're still stuck, you can sneak a look at the answer to this puzzle, working through step by step.
On the other hand, if this one is too easy for you, you can jump in and try the other puzzles here, starting perhaps with puzzle 1.