Help regarding Wordpress

I'm currently working on a project in wordpress and client want to enable its users to Register / Login into the site and want them to be able to post their articles. So that means the registered users will have limited access to Wordpress admin. Client want to restrict their admin access and make it limited so they can only create new posts under appropriate categories and edit their previous posts etc.

Users should also be able to edit their profiles etc. I've tried hard to find an appropriate plugin for this purpose but no success so far.

Anybody know a solution, I've seem some wordpress sites with similar functionality, so this is possible in wordpress but not sure how.

Any help will be highly appreciated in this regard.