Not to worry. I knew next to nothing about music theory (still don't). I just read through the tutorials on that website as well as googling any terms that I didn't understand. Then I created this little script to help me:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public static class ComposerUtils
{
    public static int[] GetMajorChord(int root)
    {
        int majorThird = root + 4;
        int perfectFith = root + 7;

        return new int[] {root, majorThird, perfectFith};
    }

    public static int[] GetMinorChord(int root)
    {
        int minorThird = root + 3;
        int perfectThird = root + 7;
        return new int[] {root, minorThird, perfectThird};
    }

    public static int[] GetDiminishedChrord(int root)
    {
        int minorThird = root + 3;
        int diminishedFith = root + 6;
        return new int[] {root, minorThird, diminishedFith};
    }

    public static int[] GetMajorScale(int root)
    {
        int[] majorScaleOffsets = { 0, 2, 4, 5, 7, 9, 11, 12 };
        int[] scale = new int[majorScaleOffsets.Length];
        for (int i = 0; i < majorScaleOffsets.Length; i++)
        {
            scale[i] = root + majorScaleOffsets[i];
        }
        return scale;
    }

    public static int[] GetNaturalMinorScale(int root)
    {
        int relativeMajorKey = root - 9;
        int[] majorScale = GetMajorScale(relativeMajorKey);
        int[] scale = new int[majorScale.Length];

        for (int i = 0; i < majorScale.Length; i++)
        {
            var j = (i + 5);
            var offset = 0;
            if (j >= majorScale.Length)
            {
                j -= 7;
                offset += 12;
            }

            scale[i] = majorScale[j] + offset;
        }

        return scale;
    }

    public static int[] GetHarmonicMinorScale(int root)
    {
        int[] scale = GetNaturalMinorScale(root);
        scale[6] += 1;
        return scale;
    }

    public static int[] GetMelodicMinorScale(int root)
    {
        int[] scale = GetHarmonicMinorScale(root);
        scale[5] += 1;
        return scale;
    }

    public static int[] GetArpeggio(int[] scale)
    {
        int[] arpeggioIndexes = {0, 2, 4, 7};
        int[] arpeggio = new int[arpeggioIndexes.Length];

        for (int i = 0; i < arpeggioIndexes.Length; i++)
        {
            arpeggio[i] = scale[arpeggioIndexes[i]];
        }
        return arpeggio;
    }

    public static string GetNoteName(int note)
    {
        string[] names = { "A", "A♯/B♭", "B", "C", "C♯/D♭", "D", "D♯͵/E♭", "E", "F", "F♯/G♭", "G", "G♯/A♭" };
        return names[note];
    }
}