Best way to change temperature

I am using PaperUI and I need to setup a way to control temperature from Openhab android app.
Now, I managed though my bidning(iotivity binding) to setup all back-end stuff but I did the temperature controlls with a Dimmer item. I think I need a Setpoint item, but I am unable to add it as I added all my other items with through xml by defining channel type and then adding it to a thing type. Setpoint just gives me internal server error.
Can anyone help me, I need something like this:

My conf file looks like this: