The monitor should already be configured as needed...however, below are directions for adjusting the input port to connect to the HDMI cable attached.
First turn on the monitor.
As indicated by the above guide, press the toggle switch once to turn on the monitor.
Connect the HDMI cable attached to the monitor to your laptop (either directly or via the appropriate adapter if your device is not equipped with an HDMI port).
Mirroring your laptop display should be "Plug and Play," however if the display doesn't come up immediately, you may need to change the monitor input port to "HDMI1."
Changing the Input Port
As indicated by the above guide, press the monitor toggle switch again to bring up the menu selection and push it to the right to select the "input" menu.
Select the "HDMI1" input port & press the toggle switch to complete the change.
If for some reason you haven't yet connected the HDMI chord to your laptop, or if your laptop is "sleeping", you may also see the dialog box below:
Press the toggle switch to the back to select "Input List" and push in to bring up the Input menu shown above.
If for some reason your laptop isn't mirrored on the monitor as you expect, you may need to make sure your laptop settings are configured for mirroring properly.
Open the LG TV display control panel from the Display Preferences.
(The above image is from a Mac, but the preferences should be similar on a Windows device as well)
Click the "Arrangement" tab and make sure "Mirror Displays" is checked. Having "Show mirroring options in the menu bar..." is helpful to have selected as well for convenient future access.
You may choose to tweak the display further from the "Display" tab, but the default settings should be sufficient.
Once all is configured everyone should see on the monitor everything that you have on your laptop screen.