how to plot straight lines in maxima

[akimatsu123]

Hi,

I am looking for help with maxima. How do i plot straight lines in maxima?

I would like to plot the lines y=x^2, y=1, and x=3 at the same time. I can get y=x^2 quite easily, but not y=1 and x=3.

What is the command for that?

Also, my gnuplot background is currently a grey-ish color I would like to change it to white. How do i do that?

Thanks,