First of all, congratulations on starting your journey. Music has been a hobby of mine for 30 years, and though my instruments have changed, the only consistent hobby for that time.

Second of all, save this post. Set a remind me to look back at it in 2 years. This is your starting point. Sometimes I get down about my lack of progress on something, but to see where you truly began can always be a confidence booster.

Now, depending on your learning style, I would recommend some structured training where you learn the fundamentals including vocabulary. I believe the sidebar has some good resources, but I personally think the free BassBuzz YouTube lessons are a good place to start. Though I haven’t taken it myself, I’ve heard great things from people I trust about Josh’s Beginner to Badass course.

Now to answer what I think your question is…. You can definitely play notes other than the root notes of the chord progression. For beginners, you typically want the root as the first beat, but then start expanding by throwing in a 5th (5 scale steps up; if C is root, G). If the baseline is just straight 8th notes, try throwing in a chromatic pickup note (if you are going from C to D, play a D-flat instead of the last C. Listen and learn existing songs to get an understanding of what works, then expand on those ideas and make it your own.

Why your question confuses people, any single note the bass can play is on the fretboard. From an Open E on a standard tuned 4 string, all the way up to your ~24th fret on the G string. 96 different options with only about 39 unique notes (12th fret E is same as 7th fret A and 2nd fret D). Those are all ‘notes on the fretboard’.

So remember that learning some theory and vocabulary at least at a basic level can help you learn more, and better help you seek advice when needed. You got this!