Depends on your keyboard, if it's C major or not. Most acoustic pianos start with A as the lowest possible white key, and then it would be A minor. But, after you find a C, yes, when you play all whites, it's C major. You actually use your thumbs for playing, too, so you start the C major scale (right hand) with your thumb, and after middle finger (E), you move your thumb under it to the next key (F), and then just play the rest of the scale (five notes, five fingers) ending up on the next C with your pinky. If you want to keep going upwards, instead of using pinky for the second C, you again move your thumb under the other fingers to the C, and do it like you did in the first octave. With left hand, you start with you pinky, and after thumb, move your middle finger over the thumb to A, and the rest of the scale (two notes left) index finger (H) and thumb, ending up on C. Someone else could probably explain this better, but perhaps this at least gives you some idea how it's done.