First thing you need to do is decide what materials to use. You can use 1X4 pieces of wood or you can do what I did and use MDF. The reason I chose MDF was two fold. One, it's cheaper. Two, if I had used the 1X4 then it would have stuck out further than my base boards and I didn't want that. I wanted it to all be seamless.
So I went to Home Depot and grabbed a few sheets of 1/4 inch MDF and had them cut it down to 4 inch strips, and some at 6 inches for the top rail. Some Home Depots will do this, some won't. You will have to check with your local store to see if they will cut it that small for you.
If they won't cut it you will need a table saw, or a friend with a table saw!
Once you have the cuts sand the edges smooth.
Now you need to decide how high the board and batten will go, for me I knew I wanted it high and I wanted to add the box detail at the top. I also used a 1X6 at the top to make the top board look a little more substantial. You also need a 1X2 board for the top to cap it off.
I actually drew on the wall to decide how far apart the boards should go. I am a visual person so this really helped me.
Using liquid nails on the back of the board and a nail gun with 1 1X4 inch nails, attach the wood to the wall. I started with the top rail going around the room making sure that I used a level to keep it straight. Like I said earlier I liked this board to be 6 inches, a little more beefy than the others.
Once you have the top on the wall you can measure the vertical boards and cut with a miter saw to the correct lengths. Using the same method, liquid nails and a nail gun attach to walls.