Hello, I am trying to make a robot I want to add some communication skill, what I have to so, I have to use some sensor or what? please help me i am trying it for very first time 
Hi,
Could you provide more details about what you are trying to accomplish ? What types of sensors you are planning to interface with your robot ?
Here is a link to our Robot Sensors category. You will find some useful information in this “How to Make a Robot” blog article series, especially the “Using Sensors” part.
As for communication, you can take a look into our Data Telemetry category.
For example, you can use an XBee module with your robot to add wireless communication between your robot’s controller and your computer.