The title field and the big Post Editing Area are fixed in place, but you can reposition all the other boxes using drag and drop. You can also minimize or expand them by clicking the title bar of each box. Use the Screen Options tab to unhide more boxes (Excerpt, Send Trackbacks, Custom Fields, Discussion, Slug, Author) or to choose a 1- or 2-column layout for this screen.

Title — Enter a title for your post. After you enter a title, you’ll see the permalink below, which you can edit.

Post editor — Enter the text for your post. There are two modes of editing: Visual and Code. Choose the mode by clicking on the appropriate tab.

Visual mode gives you an editor that is similar to a word processor. Click the Toolbar Toggle button to get a second row of controls.

The Code mode allows you to enter HTML along with your post text. Note that

and
tags are converted to line breaks when switching to the Code editor to make it less cluttered. When you type, a single line break can be used instead of typing
, and two line breaks instead of paragraph tags. The line breaks are converted back to tags automatically.

You can insert media files by clicking the button above the post editor and following the directions. You can align or edit images using the inline formatting toolbar available in Visual mode.

You can enable distraction-free writing mode using the icon to the right. This feature is not available for old browsers or devices with small screens, and requires that the full-height editor be enabled in Screen Options.

Keyboard users: When you are working in the visual editor, you can use Alt + F10 to access the toolbar.

You can upload and insert media (images, audio, documents, etc.) by clicking the Add Media button. You can select from the images and files already uploaded to the Media Library, or upload new media to add to your page or post. To create an image gallery, select the images to add and click the “Create a new gallery” button.

You can also embed media from many popular websites including Twitter, YouTube, Flickr and others by pasting the media URL on its own line into the content of your post/page. Learn more about embeds.

Several boxes on this screen contain settings for how your content will be published, including:

Publish — You can set the terms of publishing your post in the Publish box. For Status, Visibility, and Publish (immediately), click on the Edit link to reveal more options. Visibility includes options for password-protecting a post or making it stay at the top of your blog indefinitely (sticky). The Password protected option allows you to set an arbitrary password for each post. The Private option hides the post from everyone except editors and administrators. Publish (immediately) allows you to set a future or past date and time, so you can schedule a post to be published in the future or backdate a post.
Featured image — This allows you to associate an image with your post without inserting it. This is usually useful only if your theme makes use of the image as a post thumbnail on the home page, a custom header, etc.
Send Trackbacks — Trackbacks are a way to notify legacy blog systems that you’ve linked to them. Enter the URL(s) you want to send trackbacks. If you link to other WordPress sites they’ll be notified automatically using pingbacks, and this field is unnecessary.

Discussion — You can turn comments and pings on or off, and if there are comments on the post, you can see them here and moderate them.