how to plot on matlab

I came across this exercise "Let f(x,y)=(x−y)2. Determine the equations and shapes of the cross-sections when x=0, y=0, x=y, and describe the level curves."

Could anybody please tell me how to do this ?

Thanks in advance

[Stephen23]

@gao peter: hopefully you have done the introductory tutorials, which show how to create 2D and 3D plots:

https://www.mathworks.com/help/matlab/getting-started-with-matlab.html

so what exactly do you want to ask us? What have you tried so far?