Thanks for advice, have to say I didn't think that would insult anyone as the use of the phrase "newbie" didn't insult me. But NP sorry for that point taken.
A critical hit means that you roll your damage more than once, with all your usual bonuses, and add the rolls together.
The phrase above says to me you roll the extra dice and then add your bonuses. I don't read that your bonuses are multiplied.
But that's the beauty of RPGs, is the variant ways they can be played.