How to put a launch file?

edit

Hi all.

I'm trying to create a launch file as part of Hokuyo TF.

<launch>
  <node pkg="tf" type="static_transform_publisher" name="odom_to_base_link" args="0 0 0 0 0 0 odom base_link 100" />
  <node pkg="tf" type="static_transform_publisher" name="US6" args="0 7 2 1.5708 0 0 base_link laser 100" />
</launch>

Credits to Malefitz for the codes.

However, I'm wondering where should I copy the .launch file to.

Thanks for any help!