Change again to the program by clicking on a visible part of the OB1-window, or click on the PLC-symbol 
next to the gearwheel 
.
Click on the eye 
in order to activate the monitor mode.
Now you can observe the state of the in- and outputs.
Change into the first network by page-up-key and shift the window, so that your button Start and the corresponding input at the Or-box is to be seen at the same time. If you press the button with the left mouse key, you will see how the input and the Or-box will turn red.