First of all, a basic explanation of half/whole steps. These fall into the category of musical intervals, which are simply a measurement of distance between 2 pitches. Half steps (the smallest interval) equal the distance of one fret on the guitar. For example, when you play the 5th fret of the first string and then play the 6th fret of the first string, you have played a half step. If a half step is one fret, then a whole step must be 2 frets since 2 halves make a whole. In the previous example if you played the 5th fret to the 7th fret, you would have played a whole step. A scale is simply a preset pattern of half steps and whole steps. Below I have laid out the whole step/half step patterns for a major and a minor scale. The numbers represent the scale degree (or note), a "w" represents a whole step, and an "h" represents a half step. "8" is the octave which is the same note as "1", just an octave higher. I recommend working through this concept on a single string for a while, at least until you have mastered the major scale.
Major: 1 - w - 2 - w - 3 - h - 4 - w - 5 - w - 6 - w - 7 - h - 8 (1)
Minor: 1 - w - 2 - h - 3 - w - 4 - w - 5 - h - 6 - w - 7 - w - 8 (1)
Once you have mastered the single string concept, it is time to begin to learn what these intervals look like when you change strings. This can be difficult and frustrating at first but it is well worth the trouble. Begin with only one string change per scale and gradually work in more changes. Play the scale on a single string first, then use your ear to match the pitch where the string change occurs. The most important idea is to memorize what each interval looks like when changing strings and to develop a strong sense of muscle memory for each. This concept takes a lot longer to master but it will ultimately give you the ability to construct your own scale patterns on the fly rather than relying on memorizing dozens of predetermined scale patterns. Hint: the intervals will look different when changing between the 3rd and 2nd strings due to the standard tuning of the guitar.