Let’s practice with the open B and higher sounding open D string. There are two ways to play the D(h). The first is by playing the open 1st string. This is how most beginners start playing the banjo. You can also use your middle finger on the third fret of the second string.
Playing open strings are often more efficient and give you a ringing sound, while playing fretted notes give you more advanced banjo options (like slides and hammer-ons) and give you a tighter, slightly less bright sound. See this blog entry for more details.
Remember, scaffolding is available if you need help.
Don’t forget to do Musical Gym and work your way up to 120bpm.