The circuit in the photo is a simple circuit with a resistor(1kΩ) and an LED connected through a breadboard, the leads on the ends is how we will supply the votage

You could use a 9V battery for this, or you could use the DC Power Supply  

Step 1: Turn on oscilloscope, the power button is located on the lower left corner of the oscilloscope

Step 2: Find the oscilloscope leads in the drawer (first photo) then connect it to the yellow terminal (second photo). This one has to be inserted and turned clockwise to be "locked"

Step 3: Connect the ground terminal (alligator clip) to one side of the resistor and the clip the other to the other side of the resistor

This will measure the voltage across the resistor 

Step 4: Select "default setup", this will reset the oscilloscope

Step 5: Make sure the circuit is being supplied a voltage and the LED is on, once that is good, select the "1" soft-key, the one in yellow. When it is on the soft-key will light up a lime-green color. This indicated that it is reading information from the first channel

Step 6: The larger nob above the "1" soft-key will change the scaling of the vertical axis. Or you can select the "autoscale" button

Congrats! You have successfully measured the voltage across the resistor. This process can be repeated for any electronic component. You can read what the voltage is by looking at the scaling on the y-axis, or look at the top right of the display, in this photo it says "6.95V"