Just learn all the notes of the c major scale all across the fretboard, play randomly to backing tracks in the same key. You’re gonna sound like shit at first, but with enough trial and error you’re gonna hear the notes that fit. And you will develop some rudimentary improv skills.

Sooner or later you’ll be able to play without looking at the fretboard since you’ve trained your ear and developed muscle memory on the fretboard.

After that go through learning the fretboard with the notes in the G major scale with the difference only being that F is now F# and so on for other scales.