Welcome to Qubes - I hope we’ll be able to get things working for you.
The first thing to check is that you have you network cards allocated to
sys-net - you can check this on the “Devices” page in the settings for sys-net.
In the Qube Manager, find sys-net and Right click to get to Settings,
or select the Settings button on the Menu bar.
Then, look for the Network manager icon - it’s the one that looks like a
bar chart - click on it and you should see entries for Ethernet Network
and Wi-Fi networks.
If you see your router in the list, click on it to connect.
If not, there could be a software problem. Make sure that sys-net is
running. If not, open a terminal in dom0 and try to start sys-net -
qvm-start sys-net - if it doesn’t start, you may see a useful
feedback.
Open a terminal in sys-net and look at the logs to see if there are
any entries relating to those devices - it could be that you are missing
firmware that you need. Sometimes the log will tell you exactly what you
are missing, and how to remedy the problem.
Let us know what you find - and also, which version of Qubes you have
installed.