The first step to learning how to develop a bass line, is to simply play the roots of the chords. Everything else is just icing on the cake. So then it just boils down to where to play the root on the neck of the bass, and what rhythms to play.
Chords are more that one note played at a time.
You could play chords on the bass, but for the most part they will sound too muddy to be of any use. If you are playing in a band, then the guitarist or keyboard player will be playing the chords. There are a lot of different chords, and it is beyond the scope of this lessons to go into them in too much detail, but what you need to be concerned with right now is what the root of a chord is. The root is the basic note that the chord is named after. The other parts of the chord name, like the m, or the 7, just give information about what other notes are in the chord.