To add or edit content in a Text/HTML Module follow these steps:
Log in to your website
Click "pencil icon" in lower end of gray sidebar. You can click it again and make it blue to stay in edit mode which will allow you to move throughout the site in edit mode
Hover over the "pencil icon" and select "Edit Content" in the upper right hand corner or click "Edit Content" in the bottom of the module you wish to edit
This editor will open and is used like Microsoft Word - (Hover over the icons and it says what they are)
Add or Edit Content in the window.
Click "Save"