Easy. You can use a keyboard shortcut (ALT+E on PC, or CTRL+E on Mac) or the "EDIT" link and write from there.
You will be asked a password, that protects the site from unauthorized edition -- read: spambots -. Use: pH3edF0rt|-| (with a zero)
Note that the site will require you to enter an author name and won't save without one. However it won't warn you neither.