The images work fine. :) And the code excerpt you provided in your second screenshot looks alright too! However, the errors indicate there still went something wrong. Note that create_server
returns an error code, you should check it:
var peer = NetworkedMultiplayerENet.new()
var error = peer.create_server(272, 2)
if error: print("ERROR CODE: ", error)
get_tree().set_network_peer(peer)
It might help you (or us, if you post it here) to fix the problem.