it's not on C drive
Are you running Windows?
If so, you should see a netbit folder in your appdata folder.
Go to start, in the run bar, type %appdata%
From there create a netbit.conf file in the netbit folder, and relaunch the wallet. Below is a simple example of a conf file:
rpcuser=yourusername
rpcpassword=yourpassword
rpcallowip=127.0.0.1
listen=1
server=1
addnode=54.200.222.123