How do you play this?

--3-- 3 -- 3
--2-- 2 -- 2
--0-- 0 -- (0)
--x-- x -- x
--x-- x -- x

Mose specifially the notes in the parenthesis. I know that its a D chord, but I'm completely clueless as to the parenthesis
xbox live gamertag: phillips215
The parenthesis mean to keep the note held longer, basically it's saying those notes stand out more.
it actually depends of the tabber. Some say parenthesis mean to hold out a note longer, some say parenthesis mean that that note is quiet
In some cases it means continue holding the note from the last time it's played.
So in that scenario you'd want to keep the 2nd fret of the high E (Gb) ringing and then when you play the next D chord, don't strum the Gb but allow it to continue playing from the previous chord.

It can also mean play the note quieter.

Or it can symbolise a grace note, which is essentially a very quick note that comes in before another note. In this case it does not symbolise a grace note. A grace note would look more like: --(8)9-- on your tab.

So yeah... Depends on the tabber
Speed is a by-product of shut the fuck up.