i installed (Members) plugin , you can then set the capabilitys for each role, so i have a few people i let become authors, i then make the role authors , then i changed the capabilitys using the plugin to only allow them to publish posts / read / edit posts
these 3 capabilitys will anly allow them to do just that and not any other posts, but its not really what i wanted as there is nothing make it work on the front end, so i had to create a page that only can be entered by authors , in that page i made a link to the back using the a new post url , that allows them to do everything they need. i have tested it out and seems to be ok, but i really wanted something straight from the front end.