Internet (the Web) vs Paper
Writing in Page Editor is as simple as writing on desktop text editors such as Microsoft Word or Open Office. There is an important difference to be considered though.
Desktop word processors are used to create printed (or print like) content, limited to physical pages. Page Editor instead, is used to create text to be published on the Internet, and to be read using web browsers.
The most important factor to consider are:
On the Internet, pages have no physical limits. They can grow infinitely.
The same content can look different on different computers, or different web browsers. Text lines can contain more or less words, depending on specific computer features and configurations.
Users with visual or motor disabilities may want to read your texts. Keep it in mind, and look for ways to satisfy their particular needs.
Web sites and their pages have severe technical limits. They are created by programmers, using different "computer languages". These "languages" are powerful in many aspects, but have also limits that are difficult to understand by people used to the flexibility of desktop text processors. With time, you will get used to the limits, and will be able to produce quality text that works for the Internet.
The ENTER key
The first thing you should know about editing the text is the usage of the ENTER or RETURN key of the Keyboard. If you press the key, the editor will create a new paragraph. You can also use ENTER along with a SHIFT key. Pressing the SHIFT+ENTER keys simultaneously will just break the line in the same paragraph.
The BACKSPACE key
The BACKSPACE key is used for deleting mistakes, whole words or whole text. To make it easier, you can use a combination of CTRL and BACKSPACE keys. If you press them at the same time you will erase the whole word which was before the cursor.
See Keyboard Keystrokes for a list of key combinations and shortcuts.