Randy Lynn Rag is a great banjo tune written by Earl Scruggs. It's a fun tune that usually moves at a quick pace. The A part is pretty straight forward except for some cool rhythmic syncopation in the melody over the D chord.
The B part of the tune is based around chordal arpeggios.
If the basic arrangement feels tough to play use the difficulty slider to dial out the fill in notes, and focus on the core melody notes and arpeggios. Using the tempo slider to play at a manageable tempo is also a good idea. When first learning a song, make it easy on yourself. You can always add difficulty and speed after you get the basics down first.