Are you unfamiliar with integrated brake lever/shifters?
We would suggest going to a quiet parking lot, cul de sac or bike path, getting in your saddle and practice practice practice!!
The left shifter controls the front derailleur, and thus the chainrings. To change into a larger chainring, (adding more resistance) you press in with the biggest lever. When you want to make is easier to pedal, you can change into a smaller chainring, by pushing in the smaller lever.
The right shifter controls the rear derailleur. This allows you to make smaller changes on the cassette. When you want to change into a gear that provides more resistance, like on a flat stretch of road, just push in with the smaller lever. Need to make it easier to pedal? Press in with the larger lever. That's it!
This brief and helpful video will show you how to use Shimano Tourney Shifters, like are found on the Vilano Shadow:
Thank you for checking it out!