Welcome to the board, I have been there myself a few times and knew it reasonably well. As has been stated already it's around 45km due south of Udon Thani. You travel down the main road to Khon Kaen (highway number 2) and you will see it signposted when you get near. If heading down from Udon, you will then turn left at a junction (with traffic lights) and follow that road for about 8-10km and this takes you to the central Kumphawapi area.
If you are looking for anything particular, let me know and I will try to help out as best I can, hotel etc. Don't expect too much, very "non-western" and as a result, very hard to find English speaking people and western style food.
I found it a very relaxing place and liked my trips into town from my TG's village.