the first step of the basic configuration is Secure your router's access.
I don't want that there is an access from the internet.
not offer access from the Internet at all, or restrict it to certain IP addresses or IP address ranges
- by letting the SSH server dropbear and the web-Server uhttpd not listen on the external/WAN port
- by blocking incoming connections to those ports (TCP 22, 80 and 443 by default) in your firewall
But I don't understand, what's to do with LuCI. I don't understand, what I have to change with SSH.
Have you opened ports 22, 80 and 443?
I didn't change the firewall and I can't look, becauce of I can't access the router.
Then you are fine, because by default these are not open on the firewall from the internet.
Is the basic information wrong, that I have to change something?
This guide needs to be rewritten because it can be misleading. OpenWrt has already implemented most of these suggestions. Others, like key authentication in SSH, are up to the user to implement them.
Okay. What's realy nessassary to do for security?
If it works for you, then don't open any unnecessary ports or forwards. The default settings are secure enough.
That page ist in Deutsch, und mein Deutsch ist rostig.
Okay, only the page about secure access isn't up to date ... My english isn't good, too. Sorry.