The Whole-Half Scale (the diminished scale) is like any other scale, made up of notes that are a set distance away from each other.
Tone, Semi-Tone, Tone, Semi-Tone, Tone, Semi-Tone, Tone, Semi-Tone
So we will end up with 7 notes. Each of these notes we will number...
1 2 b3 4 b5 #5 6 7 1
This particular scale is also classed as a scale of limited transposition due to the nature of intervals within it. This means that it essentially repeats every 3 frets.