Great! The lesson is on the right track. You need to continue practicing to clean everything, be able to play it tight and then faster. But this is a promising take, just keep working hard.
That's exactly how you can harmonize the major scale in triads and that's how you get a major tonality. These are the triads that you can use to compose a chord progresion or a song in a major key and then create melodies using that scale. The notes can be harmonized with 4 notes, and you get 4 notes chords (those triads + 7ths).
But before that, now that you know the triads. It's a good idea to learn the triads everywhere in the neck. Let's start with the major triads.
This lesson is based on C major scale but combined with all the inversions of C major triad:
https://www.guitarmasterclass.net/solo-guit...ed-with-triads/You can start by learning only the triads.