You can add Commands to your Command Sequence by left clicking on the Command Name (in the list of Commands in the left hand panel) to add it to the end of the sequence.
You can also right click on the Command Name (in the list of Commands in the left hand panel), and then drag and drop the Command to the required location in the Sequence.
You can left click on any created Command in the central list to select it. This allows you to fill in the properties of the Command in the panel on the right.
You can right click and drag and drop any created Command in the central list to move it.
If you have a longer sequence and you want to drag and drop a Command from the top of the sequence to the bottom (or the other way around), you can use the up and down arrow keys to scroll up and down the central panel while dragging and dropping a Command. This gives the same ability as the middle mouse button on a three button mouse to users with a touchpad when dragging and dropping Commands.
You can press the cross next to any Command (apart from the Start Command) in the central list of created Commands to delete it.
You can left click on the Start Command to select it. This will show you the variables information in the properties panel.
The Commands you will find the most useful are probably the Get Data, Set Data, If, For and Return Commands (as well as the Start Command for variables).