From your store's Dashboard click the Site Designer icon in the left Navigation Menu.
The Text Block can be added to any Page on your site. In this example, we will add it to the Home Page. Using the Page: Home dropdown at the top of the Site Designer Page, make sure that your have selected Home from the list (it is the default).
On the Home Page, mouse over the page until you see the Plus Sign icon to add a new block. Click the Plus Sign icon and locate the Text section of the Add A Block menu. Open the section and choose Text, using the Add Block button.
Once your block has been added, hover over the new header section and locate the gray Edit button. Use the Edit button to open the Edit Block menu and customize it.
The Edit Block menu for the Text Block offers these options:
Header Block Controls
Trash Can Icon to Delete Block
Arrows to move block up or down the page
Make This Block Reusable Toggle
Full Width Section Toggle
Padding Top Slider
Padding Bottom Slider
Column Add Button
Column Item 1 (Sample), clicking this item opens the following menu:
Column Width On Desktop Slider
Column Width On Tablet Slider
Edit Text Button (opens Text Editor)
Column Remove Button
Gradient Type Dropdown (None, Linear or Radial)
Gradient Angle (Linear Only) Slider
Make Background Color Full Width Toggle
Background Color Chooser (Gradient Color 1)
Gradient Color 1 Range (Default 0%) Slider
Gradient Color 2 Chooser
Gradient Color 2 Range (Default 100%) Slider
Text Color Chooser
Link Color Chooser
Link Hover Color Chooser
Make sure to click the Done button at the bottom of the block edit section to save your changes.
Additionally, you will need to click the green Publish button at the top of the page to make your changes live on your store.
Another related Block option would be the Text Image Block.