In fact this is a pretty easy song on bass, just follow the chords on the guitar:

Intro; A - D (2x)

A - D - Bmin - E
A - D - Bmin - E
Fismin - D - Bmin - A - E
Fismin - D - A - E

That's all, but here's a little trick to play this song on your own, without the help of 
other musicians...just you and your beloved four-string !! (great exercise too):

Intro:
     (A)       (D)
G]--18--18----18--18-|
D]-------------------|   2 X
A]------------17--17-|
E]--17--17-----------|

Song:
      (A)       (D)       (Bmin)    (E)
G]--18--18----18--18----19--19----13--13------|
D]--------------------------------------------|     2 X
A]------------17--17--------------------------|
E]--17--17--------------19--19----12--12------|

    (Fismin)    (D)     (Bmin)  (A)   (E)
G]--14--14----11--11----19--19---18---13--13-|
D]-------------------------------------------|    1 X
A]-------------------------------------------|
E]--14--14----10--10----19--19---17---12--12-|

    (Fismin)   (D)        (A)       (E)
G]--14--14----11--11----18--18----13--------------|let ring
D]------------------------------------------------|         1 X
A]------------------------------------------------|
E]--14--14----10--10----17--17----12--------------|let ring


Have fun !!