To create and edit your Splash Pages, please activate the related option into your SSID.
To do so, follow the steps described below in your Classic Hotspot Cloud account:
STEP 1
Click on your Network, than on the SSID you previously created (or create a new one following this article: Create an SSID ).
STEP 2
Click on the Wireless Security tab >> you will see the following picklist:

STEP 3
Select "Splash Page with Editor".
You will see new tabs appear, just select the "Splash Page" one and enter into the Editor clicking on the button.
NOTE
You can also access to the Splash Page Editor from drop down menu that you find under your account name in the top-right corner.

Related article:
How to create a new splash page