Seems that your frame doesn't have a hole, there are just those "ribs" to guide the mechanical shifting cables. So you must remove to bottom bracket cup from one side to put the junction box inside the frame.
You still need to get the battery and FD wires from to the junction box to the components - the easiest way i can think of is drilling the same "ribs", so that the path follows the wires logical route. I will try to snap a picture from my frame.

JensW
How that solves the placing of the B junction? If I stay external, the box I have is not good. I can move the battery let say on the seat tube, can you explain what am I solving by that?

If you mean to use the internal B junction and to follow what Omiar said so the box will seat inside the frame and the battery wire will run up inside the seat tube but then where and how I hold the battery there, what do you mean under the saddle.
Thanks

Here are the pictures after the job was done. Everything running inside. The housing holes were expended to take the wires in. The chain stay was drilled in the back of it for the RD wire, the existing hole of the FD in the BB area was widen a bit to take the wires of the FD and the battery.
Comments are welcome!