Now that your site is set up and you've added users, all they need to do to add a new post is log in and start typing:
To add a new post (or update), type in the box at the top of the screen. Type or select tags below the textbox and click on the Post it button.
You can add different styles of post (or post formats) by clicking one of the buttons above the textbox before typing in your text:
Selecting Blog Post means you can add a title to your post
Selecting Quote means you can add a quote and citation
Selecting Link means you can add a link without any other text
To reply to a post, simply click on the Reply link next to the post and type your response.
Whenever someone replies to a post, the post author will receive an e-mail notifying them, meaning they can reply back if they want.
The P2 theme formats the different types of post differently. The following screenshot shows how my site looks with a quote, a blog post, a link, and some updates with replies...