From http://superuser.com/questions/1147554/how-to-access-apache-server-running-in-virtualbox-from-host
The port forwarding feature accessible from the Network advanced settings of your virtual machine allows you to selectively expose a port of your virtual machine to your host.
This way, you can setup virtual machine port 80/tcp (http traffic) to be easily accessible from your localhost port 8080.
Below is an exemple for this setting:
Name: webserver
http Protol: TCP
Host IP: 127.0.0.1
Host Port: 8080
Guest IP:
Guest port: 80