This is one dull shower, no excitement here! Lets spice it up alittle, and add another shower head. We'll position it opposite this one. To begin, get rid of that shower head and save it for later, or replace it with a massage unit.
Time to get started, First remove the shower head. Make sure you put TEFLON TAPE on all threaded joints.
Now put the two way value in.
Put shower head on.
Now put the 1/2" to 3/4" adapter on that so you can use a washer hose to get the water to the new shower head.
Like this.
Put the washer hose on the wall just like this.
You are almost half way there.
This is the value that will let you turn off the new shower head.
Put the value on the washer hose.
There is one part of this job that you will have to do some soldering I will  show you how to do that just go to this link.
Now that you now how to soldering we can put the rest of it together. Just put it on the value.
Now put the new shower head mounting bracket on.
Put the shower stem on.
Put the new fun shower head on.
Now you have a high priced shower for not alot of money.