bill ive been pounding out kids songs like you wouldn't believe. it's very easy. why don't kids songs get to have the black keys? why are they special?
there are 2 ways to be introduced to black keys. let's start by staying in the key of C. play the first 5 notes, up and down, c,d,e,f,g,f,e,d,c. this is part of the "key of C", specifically the key of C major.  actually, it's all 7 notes all the way up. c,d,e,f,g,a,b,c. but let's just look at the first 5-- c,d,e,f,g. try JUST c, e, and g, all together at the same time. that's a chord. the name of that chord is C major. it is like your home chord in the key of C. ok great. now, plot twist, let's try a black note. instead of E, play the black note to the left of it instead (that note is called "E flat" which is written as E♭ or Eb if you don't have the flat symbol handy... whenever i type Eb it means "E flat") ..... so any time you would have played E, play Eb instead. so going up the first 5 notes of the C major scale but switching in Eb instead, you get C, D, Eb, F, G. and back down, G, F, Eb, D, C.  you'll notice it has a darker sound, like "sad" basically. this is called C minor. try the chord, C, Eb, G. that is a "C minor" chord. the C minor scale going all the way up is usually C, D, Eb, F, G, Ab, Bb, C. but the top part of the scale has a few different options that come into play that we'll worry about once we start seeing them actually in songs. mess around with the notes in C minor a little bit, especially the first 5 notes. for a challenge, see if you can figure out "the ants go marching 1 by 1", which is a kids song in a minor key. hint: you will need to include notes all the way down to the G below your root C. hint: the word "march" will be on C, and the word "one" will be on Eb. let me know if you can figure this out