How to can I configure the port forwarding or open some port in XG Firewall 16.05 RC1?

HI ArtemioAmador, 

You may create a DNAT rule and specify the ports you wish to forward . 

 Hi Aditya Patel,

Thanks for your help.  Another thing, where can I download the v15 MR3? I still prefer to used this version actually..

You can get all images from here https://community.sophos.com/products/xg-firewall/b/xg-blog

However, I recommend that if you don't want to stay with v16.05RC1, that you go with v16.01.2. This cleans up the UI, adds over 100 features and fixes.