I tried putting the internet cable from my desktop into the port on the laptop but I couldn't bring up the internet by clicking on the Explorer icon

Do you mean the cable coming from the cable modem into the desktop? You took it out of the desktop and connected it to your laptop? If that's what you did and it didn't work, then you need to check with Comcast support. If you did something else, please explain.

After you plug the ethernet cable into your laptop try shutting down and restarting the laptop. Maybe since no internet has ever been hooked to it, it doesn't install the drivers at boot up unless it detects a connection first.