Once again you'll recognise this Major Scale Pattern! It's exactly the same pattern you've played for A Major (and C Major of course) only here you begin on the Root Note D on the 10th fret).

Take a look at the scale degrees. 

What notes are at 1, 4 and 5?

D, G and A

As we established above, we'll use Roman Numerals when talking about chords - So, 1, 4 and 5 is of course I IV V and in this case (the key of D) our I IV V chord progression is made up of the chords D, G and A. However, the 12 bar blues progression predominantly utilises the dominant seventh chord and it is those (the 7th chords) that you'll play for this 12 bar blues in D.

You'll see Dominant Seventh Chords written like this: - D7 G7 A7 (subsequently the progression should be written I7 IV7 V7)