Hi Scannie --
I just got back into town and saw your question and the replies. The replies have good advice, but might be a bit intimidating.
Most how-to articles begin with the C scale (AKA "C Major"), perhaps because it's the easiest to picture and play (i.e., all the white keys):
https://www.musicradar.com/how-to/music-theory-notes-intervals-scales-chordshttps://www.soundonsound.com/techniques/musical-tricks-transform-your-tracksIn the first article, you'll see seven chords (3 note triads) which use the white keys: C, Dm, Em, F, G, Am, Bdim. Don't worry about the Bdim (diminished) chord right now, but try playing different combinations (progressions) of the C, Dm, Em, F, G, and Am triad chords. You'll find that zillions of songs are based on some combination of these chords!
And guess what! If you start with Am, you'll find that you can create minor key (sad) songs with this scale, too. That's why the relative minor key to C major is A minor.
Once you're comfortable with C major/A minor, try other keys/scales. The same basic theory applies.
Hope this helps -- pj