>>548643#horriblesubs is not a server, it is a channel (chat room). Newserver is also likely not a server but something you put in.
First be sure to set yourself a username before attempting to logon to a server.
When you set up your IRC client you should be able to select which server you want to connect to. It looks like you want to connect to
irc.rizon.net select that to connect to that server. Close configuration and click the connect button. Also, the program should also have an ability to query the irc network and pull up a list of connectable servers. Think of it as a bunch of computers hosting a server at a certain location on the Internet to which a client connects and creates chat rooms.
Once connected to the server of choice and you know which chat room you want to enter you type /join #chatroom in the console tab. In your case you would type /join #horriblesubs and it would connect to that chat room. Alternatively you can click the channels button which will give you an option to list all the available chatrooms that are hosted on that server.
