You will need to spend some more time with GUI of Xubuntu !
First thing..
You are not able to access internet as your card seems to be detected but has not been assigned proper IP etc.
You find some network setting option and there add required info.ie. gateway, dns, ip to the eth0 (if you hv 1 NIC only)
Hmm,
fdisk -l
can you show your partitions and mount point ie. name given to partitions.
Hidden from desktop ? means not on desktop ?
Try creating a new link / shortcut and then type command which invoke mozilla
PS: I have not used GUI from long time so all above info is on assumption..