hey esteban,
there's a setting for that in the easysocial backend.
have a look at settings -> users and in the box called "authentication" there's the setting "login redirection" where you can set it to any page you want or select that the user should stay on the same page.
http://screencast.com/t/0csDhJ1SaH0
of course that only applies when you're using an easyscocial related login, for example the login page itself or the easysocial toolbar. if you use a different login module or 3rd party app then of course you have to configure it somewhere else.
hope that helps