How to set access to virtual servers?

[Munis]

Hello dear experts ! I have some trouble with this task :

I have  1 External (WAN) ip and  4  virtual servers(moodle,openmeetings,freenas and mail) so, how can I  establish access to  them throuth NAT or port forwarding ? or maybe reverse proxy?

I need something like that  77.XX.X.XX to 192.168.0.5,192.168.0.6….............

Thanks !