The C major scale has no sharp or flat notes. This major scale key is on the Circle of 5ths - C major on circle of 5ths, which means that it is a commonly used major scale key.
To play the C major scale ascending, start with the root note C and play the notes in order: C - D - E - F - G - A - B - C. Then, go right back down the scale: B - A - G- F- E - D, until you've made your way back to the lower C.
