the intro and verse is a Db to a D. during the intro he plays this as an open D chord shape( the Db means you just move the open D shape down a fret)and then goes to power chords for the verses.
the chorus goes between a G an A and D in standard 4th and 5th note form. (G being the 4th note in the D scale and A being the 5th).
and for the solo just have some fun in D. It's not too hard to pick out what Brian does anyway as long as you stay in D.
By the way, when playing the open D flat make sure you let the D string ring and slide(dont pick) up to the D. then just gointo the power chords( but pick these).
i hope this makes sense.
just ask if you have any problems.
thanks.
p.s sorry if some of this sounds basic or useless but i tried to be a simple as possible as i dont know what level your are on.