using bro-1.5.3

I am a new user of bro ids , wanted to know how to run a policy script. Iam running bro-1.5.3.
what should be written after running ./broctl command to run any script.

I am new to Bro-1.5.3. I installed it on Ubuntu 10.04 which is running as a guest OS on virtual machine and my host machine is windows 7. I am doing the UDP flood from host machine to guest machine and wants Bro to log it so I ran command

bro -i eth0 udp.bro

then i chekcd /spool/bro/conn.log

but sometimes this file is empty or it says output can’t be shown due to character encoding problem.
I have checked networks.cfg file also for network addresses . is included in it also my guest machine’s ip is set to and host machine’s ip is so I think there is no problem due to this.