One of the blocks that will most likely be used most is the manual Main story-block. It is marked in red on the following front page example:

To add this block, log in to the eZ Flow front-end editing interface and edit the front page. Select the correct zone and select Main story (manual) in the block type drop down list.

 
The following block will appear where you can name your block. It is also possible to set the overflow of this block (as shown in the drop-down list in the next screenshot), and the rotation frequency of the images, set in minutes, hours or days.

 
 Click "Send for publishing" to complete the procedure.