On the left Menu, Click the Posts menu. A new page will appear with empty list.
To make a new post. Just click at the top right button named Add New. A new page with a form will shows.
Insert the Post title, Post content, Pick a Category and Publish it.
There are some options, Category, Publish status and Dates. You can modify it as you like.
After a post is submited back to the posts manager and see if the post is submitted succesfully.
To edit or delete the post, there are some options at the right of the post. Edit, Delete and If you want to modify it massively, jusst check the checkbox and click the submit button.