How to put members area on my site

There is many ways by which you can do but it needs the knowledge of css and java script along with other server site languages like php or perl or ajax. You also need a data base to record and have those things like of oracles or mysql. Better is is to use facebook twitter conect to have signup etc.

Either try to learn things about HTML, PHP, and MySQL first or just use the ready-to-use script..

It depends on what programming software you're using. If it's html, some developers say you need to use form tags. But you need a database for that. Perhaps you can also check autoresponders that are available online. Then you can embed them in your site when you ask visitors to subscribe or sign up.