IP Camera Port Forwarding

This is very newbie question.

I’m an intern at a company that offer networking solutions to it’s clients. At on of the premises, he has a RouterBoard 2011uias running OS v6.30.4. One of the clients has set up a camera t her premise and would like to view them remotely.

Between the Mikrotik router and the cameras is another router(that serves her premise), then the DVR.

I’d like to make this happen, what important information do you need to aid me make this happen?

This article should explain how to do this:
https://wiki.mikrotik.com/wiki/Manual:IP/Firewall/NAT#Port_forwarding_to_internal_FTP_server

Here is also another example:
https://wiki.mikrotik.com/wiki/Tips_and_Tricks_for_Beginners_and_Experienced_Users_of_RouterOS#Port_forwarding_on_RouterOS

Be very careful with cameras directly attached to the Internet. Unless you are willig to help botnets… I would advise to use VPN to make a secure connection to the network over which the camera (or nvr?) can be connected.