First enter an expression, for example: x^2+3*x

Next select which function you would like to plot. There are 4 options.

Then select the domain and range of the function using the sliders.

Once you are ready, click submit.

*** SIDE NOTE:

If you see a plot that does not resemble what you inputted, for example you see a 3d plot or a eng-130 plot. just run the app again. I dont have anything related to eng-130 in my code or any 3d plots, but it still get them in my plots. I think this is due to some bug in MecSimCalc itself.