In both measures you should play the 2nd string open three times. The first two notes in each of these measures are quarter notes. The last note in each measure is a half note. The line coming down from the note tells you the time value of the note. The quarter notes reach all the way up to the note, whereas the half note is designated by just a small line underneath the measure.
Most banjo music consists of quarter notes and eighth notes.
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.