Rubik's Cube Face Rotation?

For my school project I decided to chose to create a Rubik's cube sim in Unity 3d. Due to pressing personal reasons, I was unable to even get started, but the project is still due. With the deadline closing in, I tried my best to find an easy tutorial or guide on how to do this, but there wasn't much that I could understand with my basic knowledge of Unity and c#. I would not like to just use somebody elses program. What I did manage to find, was a model of a Rubik's cube which I imported. All I need is to create a script where when a certain key is pressed, U for example, a face is rotated. I know many of these threads already exist, but I couldn't really understand any of them. Please try to keep it a bit basic, as my programming knowledge is limited, but I'm willing to learn quickly as the deadline is very close. If it helps at all, each cube on the Rubik's cube model that I found online is it's own designated mesh. Thanks.