i m going to create a dating web site. it's online game. there are will at first registration, chat and the game, where people can ask question and random users (3 boys to 3 girls) answer on each other at real time.
If I understand your site correctly, you want some people to be able to post questions in a global chat and then separate into "rooms" 3 male and 3 female users which will be able to answer those questions through local chats. Aside that the site will also work pretty much as a social network.
I think the whole site wont need anything more than html, css, php, mysql and jquery (including the ajax technique). You could use ape, socket.io or something similar if you want to, but it's not required.
Some people recommended me use NodeJS. Do you know about it? I read that I have to create my server to make chat, for example. I don't understand, how will it work in Internet, not my local machine? Do i have always turn on my computer in order to stay turned on server? Where users info and messages will be situated? in mysql?
In jQuery it's easy: no server and js+php scripts to go with mysql.
I'm not familiar with node.js . You may consider using it since you will need a host running 24/7 anyway to keep your site online all the time so having the server required for it running non stop shouldn't be a problem.
My personal advice though would be to stick with what you know for now so you wont have problems debugging your site and check other methods on the side until you can use them with ease. Then you will also be able to see if it's better to keep it the way you have it or change it with something else like node.js .