Running concommand from client file to server file

[jamesjasl]

Hey there. So basically I've been working on a VGUI script.
I made it so that it stores info from dropdown boxes etc. but then on pressing done button, send a console command "say hello"
This didn't do anything, a friend told me you can't do it in a client file.

So how exactly do I make that happen? I understand its to do with networking but i'm still confused.

[Spar]

CLIENT
net.Send

SERVER
net.Receive
net.ReadString
file.Write