To Post a Message: Get into Forum 1 (if you are not already there). Click on the "Post" button (you may have to scroll down to see it). Then give your message a title and type your message in text box. When you've finished your message, scroll down and click on the gray "Submit" button.
To Edit a Message: Click on your posted message. Then click on the green "Edit" button on the top of the screen. After you've made changes to your text, scroll down and click on the "Submit" button.
To Reply to a Message: When you are reading a message you'll notice a purple "Reply" button on the top of the screen. Click on "Reply," type your message, and then click on the "Submit" button at the bottom of the screen.