Dragging and dropping a Saved Block adds a Saved Block to your email (Fig 1). 

Fig 1:

Saved Blocks can be edited by clicking on them, then clicking on Block Settings (Fig 2). 

Fig 2:

In Block Settings, you can do the following (Fig 3): 

• Save Block: Turn this block into a Saved Block. 
• Read Only: Toggle the block into Read Only (default is OFF) 
• Don't Stack Mobile: Toggle if columns are stacked on mobile (default is OFF) 
• Swap Columns: Swap the position of columns. 
• Colors: Adjust the background and body color of the colors. 
• Typography: Adjust settings like font family, weight, and alignment for both the Title and Body Text in the block. 
• Spacing: Adjust spacing in the block. 

Fig 3:

If you have no Saved Blocks, then you'll need to save a Basic Block first. Drag a Basic Block into your email, customize it, and click "Save Block" under Block Settings.

To learn more about the types of blocks, read the corresponding article:

• Blocks - Basic Blocks
• Blocks - Preset Blocks