Ar tag find and go

I'm doing car with ROS. My car have to find AR TAG with IP camera app. Then after when car will see AR TAG and go forward to AR TAG. I done everything gscam, my launch files, cameras except motor code.
I've one of code but i've to modify this code. Could please give me advise ?

if( !find_next_target ) {					// if we're in target tracking mode, drive towards the target
      distance_err_cm = LINEAR_TARGET - distance_cm;
      ino_drive.linear.x = -distance_err_cm * LINEAR_GAIN_P;  	// ranging +-50cm will have speed contorl mapping
      z_angle_err = atan2( right_offset_cm, distance_cm);
      ino_drive.angular.z = z_angle_err * ANGULAR_GAIN_P;
    }else {							// if we're in the "find_next_target" mode, do something here
	// do something to search the target	
    }

For the ignorant please define ROS and AR TAG.

Weedpharma

ALL, please remember that not every one knows the acronyms for all areas of interest.