Ok maybe screenshots help :).
First of all, choose in BitComet Preferences any port between 50000-60000 or click random but you will need to remember this port, and put it in the field indicated on sceenshot below (if you didn’t choose random):

Then you need to go to PC-CILLIN and open it. Go to Network Security:

Then you need to go to Personal Firewall

… and if you didn’t change anything here, you probably need to go to Direct Connection and change its rules upthere - I assume here that your default rules are Direct Connection, which is done after intalling If you don’t use Direct Connection as a default rules, edit different one. So click Direct Connection to choose it and then click Edit button:

IMPORTANT!!! When you finish putting rules in next few steps, you will be back here and you must click Apply, because everything will be lost !!!
You will see Add/Edit Personal Firewall. You have to choose and click Exceptions field and you will see many and many names of programs which are already put in it and have particular internet rules. What you need to do now is to find names which are connected to BitComet (BitComet -a BitTorrent… in my case). When you find it click one of them, lest say upper one or that one which you can see, click it to choose. Then Go to top of that list and click Edit button:

Change everything exactly the way you can see in the picture below but put correct port number in the field Specified Port(s): 56789 - on the picture.

Now, if you don’t see second rule for BitComet yopu must find it. It must be somewhere there between all rules. If you find it keep rules according to those on picture below:

REMEMBER!!! After setting the rules, the button Apply must be clicked to confirm changes !!! If you forget to do it, everything will be lost !!!

That’s it. You should have configured PC-CILLIN correctly for BitComet afterwards, if you went through steps.