Now more on topic...
You can't really expect much DPS from a healing spec. It's not realistic or reasonable for your guild officers to ask this of you.
The best you can do is have 2/2 Train of Thought, Holy Fire > Smite while DoT is up > Penance on CD. Do that while never letting your DoTs drop off for long.
Now, if you plan to stick with this you need to spec like this - http://www.wowhead.com/talent#bfGR0RsbcRbo0hZG00b