There are two ways to justify your paragraph.
1. Using a HTML snippet
Go to the “Text” editor of your WYSIWYG. Then, add a text-align: justify style to your <p> tag.
Example:
<p style="text-align:justify;">
YOUR TEXT HERE
</p>
2. Using a shortcut key
On your visual editor, look for the ? icon and then click on it.
After clicking, the Keyboard Shortcuts will display. Scroll down a little bit to find the justify shortcut key.
Use the justify shortcut key (Shift + Alt + j) to justify your text.