To tell Design Master Electrical how the one line devices are connected, go to
DM Electrical 
One Line Diagram One Line Device Connections
The One Line Device Connections dialog box will open. Set Step 1 and Step 2 to match those shown below. (The specifications that you will need to change are highlighted in yellow in the screen shot below. They will not be highlighted in your working dialog box.)
Next, press Change Number of Poles... The Change Number of Poles dialog box will open as shown below.
Select Three and press OK. Design Master Electrical will return you to the One Line Device Connections dialog box, which should now match the one shown below. The only change should be the one highlighted in blue in the screen shot below.
Press the Step 3: Press this Button to Connect the Device button. The One Line Device Connections dialog box will be updated and will now match the one shown below. The only change should be the one highlighted in blue.
Now repeat the steps above to connect panel L1 to transformer T1. The steps are reviewed below.
In the One Line Device Connections dialog, which should still be open, set Step 1 and Step 2 to match what is shown below. (The specifications that you will need to change are highlighted in yellow in the screen shot below.)
Press the Step 3: Press this Button to Connect the Device button. The One Line Device Connections dialog box will be updated and will now match the one shown below. The only change should be the one highlighted in blue.
Design Master Electrical has the ability to calculate fault current and voltage drop. These calculations require the distance between panels and transformers to be specified. You can either manually input these values in the one line device definition dialogs, or have Design Master Electrical calculate them for you. In this tutorial, we will have Design Master Electrical calculate them for us.
To do this, you must insert the panels and transformer on the drawing. This is done by inserting the plan view blocks.