Not sure what you are trying to do from the limited information, but I'm guessing you need something like AMCL http://wiki.ros.org/amcl. Where one of the topics you need to provide is the map generated by for instance hector mapping. You can perform the mapping procedure once and after that just use a localization method that uses the generated map.

Hi, first of all thank you for your reply. I am using http://www.clearpathrobotics.com/assets/guides/jackal/navigation.html jackal. I did mapping with hector mapping. Also I installed AMCL. However I want that to localize itself automatically instead of me using the 2D Pose Estimate. Is there anyway to do that ?

It sounds like you want to do global localization first. I believe this is a setting in the AMCL package. Are you familiar with particle filters for localization? I highly recommend you to read "Probabilistic Robotics" by Dieter Fox, Sebastian Thrun and Wolfram Burgard. This will give you a basic understanding of how probabilistic localization methods work. If you care more about fast implementation than a full understanding I can recommend looking for the keywords "ROS" "AMCL" "Global Localization" and "example" and see what comes up :).

Thank you again. I am new in ROS. That's why sorry for my questions :) However, I've tried global localization but it does not localize itself in correct place. Do you have any suggestion or where should I check ?