I would suggest you to start from this Tip & Tech Document in Tizen developers forum. This document explains step by step how to use device sensor in Tizen native application including creating event listener, registering callback functions, reading data, etc. You may download the project (.zip) and import in Tizen Studio.
Light Sensor in mobile native is implemented here, but the process for Pedometer in wearable native is also the same, just change in some parameters. Add the healthinfo privilege and pedometer feature in your config.xml file.
<feature name="tizen.org/feature/sensor.pedometer"/>
<tizen:privilege name="http://tizen.org/privilege/healthinfo"/>
Check the API references for details, you would find all the API functions there.