Here's the intro.  It's a fingerpicking style called "Travis picking" 
named after Merle Travis who apparently came up with it first.

Essentially, it's just variations of C and Am, alternating between open, 
1st fret and 3rd fret on the 2nd string with your index and pinky.

                                                  
|---------------|---------------|-----------------
|-1-------1-----|-0-------0-----|-3-------3-------
|-----0-------0-|-----0-------0-|-----0-------0---
|---2-------2---|---2-------2---|---2-------2-----
|-3-----3-------|-3-----3-------|-3-----3---------
|---------------|---------------|-----------------
                                                  
                                                  
|---------------|---------------|-----------------
|-1-------1-----|-0-------0-----|-3-------3-------
|-----0-------0-|-----2-------2-|-----2-------2---
|---2-------2---|---2-------2---|---2-------2-----
|-3-----3-------|-0-----0-------|-0-----0---------
|---------------|---------------|-----------------
                                                  
                                                  
|---------------|---------------|-----------------
|-1-------1-----|-0-------0-----|-3-------3-------
|-----2-------2-|-----2-------2-|-----0-------0---
|---2-------2---|---2-------2---|---2-------2-----
|-0-----0-------|-0-----0-------|-3-----3---------
|---------------|---------------|-----------------
                                                  
                                                  
|---------------|---------------|-----------------
|-1-------1-----|-0-------0-----|-3-------3-------
|-----0-------2-|-----0-------0-|-----0-------0---
|---2-------2---|---2-------2---|---2-------2-----
|-3-----3-------|-3-----3-------|-3-----3---------
|---------------|---------------|-----------------
                                                  
                                                  
|---------------|---------------|-----------------
|-1-------1-----|-0-------0-----|-3-------3-------
|-----2-------2-|-----2-------2-|-----2-------2---
|---2-------2---|---2-------2---|---2-------2-----
|-0-----0-------|-0-----0-------|-0-----0---------
|---------------|---------------|-----------------
                                                  
                                                  
|---------------|
|-1-------1-----|
|-----2-------2-|
|---2-------2---|
|-3-----3-------|
|---------------|