An example of a scale is a Major Scale. A major scale has the following arrangement of half-steps (H) and whole-steps (W):
W-W-H-W-W-W-H
If we start this pattern on the note D we get a D Major scale: D, E, F-sharp, G, A, B, C-sharp, D.
This is just one of the many possible scales but all scales work in the same way.
List of Scales: