hello,
first of all,I want to notice you that the information you gived is not enough to us to offer you a security NAT policy.As you know,firewall is a security device,every policy you configured on it must be considered a lot,it's more recommand that you provide a simple topology.
here is the document link of USG6000 series,
http://support.huawei.com/hedex/hdx.do?docid=EDOC1100013380&lang=enyou can refer the documentation and configure it according to your actual situation.
what's more,I suggest you enable https on CLI,and configure NAT on web interface,it's more convience.