Option 1. You´r granted User-Shell access / you got no more problems - you can change stuff.
Option 2. You dont get shell but FTP to /maps and /.teeworlds
2.1 You can upload all needed maps trough FTP /maps and change default config by uploading it to /.teeworlds however you cannot run modded servers if you are not granted shell access to compile code in /teeworld-X
Best thing to do is this:
Put a restart.sh at /teeworlds location and insert
# restart.sh file
ulimit -n 1000000
while :
do
nice -n 5 ./teeworlds_srv
sleep 5
done
Start with screen -d -m ./restart.sh
If you experience lags root hast to renice -5 PID of your TW server
Now you can play with configs on your server trough F2 Rcon console and if you got problems just 'shutdown' (rcon command) the server and it will be online again 5sec lader
If you got problems with this: 145 00 77 88 (ger too or eng or dk or whatever)
But dont ask me if you got just some idiotic question google can easily handle.