VirtualBox is a virtualization software only. How do you want it, "the Internet" come from? That is still the primary task of the virtualized operating system (and the network port of the host system). In the VirtualBox configuration you only need to ensure that achieve the virtualized network adapter using NAT or bridge the desired host network can. IIRC the default is NAT anyway, so far as it should be about VirtualBox no problem. Lack of meaningful problem description can one help but be bad.