C# rotating a 3D object left&right using mousedrag

Hello!

I'm currently making a little game in which the player has to navigate a physics-affected cube inside a square maze level by rotating the level.

I am still a novice at C# scripting and don't know how to get the results I am looking for.

What I specifically want to have is that the player can rotate the level by pressing and holding the left mouse button and dragging the mouse left and right. An extra little detail that I'd really like to have is that the level doesn't immediately stop rotating, but that the level instead slows down to a stop over an amount of time.

Thanks to anyone willing to help.