make dock more transparent/translucent?

hello
is it possible to make the dock less opaque. it's very grey and (because i wanted a mac for so long) i had something called object dock for PC, which basically is there same thing. on this object dock, however, it was possible to make the grey background of the dock more transparent, and i've looked everywhere on my mac (which is new so still don't really know what i'm doing!) and haven't managed to find a way to change it
if anyone can answer my question that'd be great
thanks
tom