In a different thread on this forum I have posted a ROS node that is just about as simple as a node gets. This node ‘could’ be used as a sort of starter template for the node for your project.
You would change package name and other things but then would have to do the large task of adding in the radar interfacing code and then conversion of radar data to ROS messages.
this is the simple ‘starter basic code’: https://github.com/UbiquityRobotics/sonar_detector
So the specifics of this node do not apply to the large amount of Radar interfacing nor does it apply to the specific type of ROS message(s) you would output BUT this node shows a lot of the ROS mechanisms you for sure would have to have in your node for basic ROS message processing.
This is a small part of your task, the huge amount of your task is wrapping the radar driver code and then forming meaningful messages to be published.
You would be wise to search for an Existing ROS message that would match your needs and even better a Ros Message that has RVIZ support already. So I suggest you look at sensor_msgs and try to find one that would have the type of output you would want for your Radar and see if it has support in RVIZ. This is up-front homework and time well spent.
do not invent your very own message unless none of the messages in sensor_msgs will hold the type of information you want in your radar.
See and study these messages: http://wiki.ros.org/sensor_msgs
Specifically read up on these messages: Range, LaserScan (2d radar) or the PointCloud ones which can deal with 3d data points