x host question

[R. Welz]

Hello.
How can I connect to a linux system running XFree86 4.3?

I tried:
Robert-Welzs-Computer:~ welz$ xhost +192.168.2.128
192.168.2.128 being added to access control list
Robert-Welzs-Computer:~ welz$ telnet 192.168.2.128
Trying 192.168.2.128...
Connected to 192.168.2.128.
Escape character is '^]'.
Password:
You have new mail in /var/mail/welz.
Last login: Thu Jun 17 04:54:28 from G4
Have a lot of fun...
-bash: Hz: command not found
welz at linux:~> opera
_X11TransSocketINETConnect() can't get address for 
Robert-Welzs-Computer.local:6000: Name or service not known
opera: cannot connect to X server Robert-Welzs-Computer.local:0.0
welz at linux:~> _X11TransSocketINETConnect() can't get address for 
Robert-Welzs-Computer.local:6000: Der Name oder der Dienst ist nicht 
bekannt

Many many thanks for help!
Greetings,
Robert Welz