This song is amazing. Standard tuning (EADGBE).

First bit (the higher-up part):

E:------------------------|------------------------|
A:------------------------|------------------------|
D:------------------------|------------------------|
G:--------8s10------------|----10-10-10s8-8-8s7----|
B:---------------11-------|------------------------|
E:------------------------|------------------------|

E:------------------------|----------------------------|
A:------------------------|----------------------------|
D:------------------------|-------------------------8--|
G:--------8s10------------|----10-10-10s8-8-8s7--------|
B:---------------11-------|---------------------8p6----|
E:------------------------|----------------------------|

Second bit:

E:------------------------|
A:------------------------|
D:--8s10--5---5s3--3--3s8-|
G:------------------------|
B:------------------------|
E:------------------------|


And that's it! Just repeat those two parts. Make sure to add lots of reverb to get that 
lovely ethereal feeling.