To connect to a localhost server, you need to run the luniserver.exe file. This will launch a console window that should say things like «World started! Listening on: 2002». If you’re still not able to extract the file, this will be impossible.
Also, I recommend you to use Jonny’s server. Just click on the green link at the bottom of the page that says «Jonny’s Server online». That will take you to his login page, which you should register an account. Then, login. Go to Forums in the toolbar, then click on the topic «[INFO] How to join this server», and follow the instructions.
I hope this answers your question.