Although there are no eighth notes written in these examples, take a look at some of the song arrangements and you will notice many eighth notes. The eighth notes have stems that are connected to adjacent notes. If you play the measure above correctly it should sound like the beginning of Jingle Bells. Play it and see what you think. Written above these two measures of tablature are chord diagrams.
Every song has a chord progression.
Chord diagrams are basically just a picture of where the fingers of your left hand should be holding down the frets. If you hold your banjo straight up facing you and look at the first four frets, that is the picture that the chord diagram is showing. In more advanced playing up the neck of the banjo the starting fret is denoted by a number on the left side of the diagram, but you don't need to worry about the for now. The first diagram above shows the G chord. Since the banjo is tuned in an open G already, playing all of the strings open gives you a G chord.