You won't see a wireless icon, and that's normal.
As far as the Ubuntu installed in your VirtualBox is concerned, it has an Ethernet connection, even if the connection on your physical computer is wireless.
Now, if you don't see any icon at all, it's possible that your virtual network is disabled or turned off. Double check your VM settings and make sure that there's a virtual network adapter installed and connected, and that it's not set to "Host only network" if you wish it to have internet access.
More information is available in the VirtualBox documentation