How to change plotstyles?

When I plot to pdf, everything in my viewports is a gray light tone, hard to see. How do I change this?

you'll need a ctb file with all the colors set to plot black

Where do I get one of those?

Your plot settings window should give you the option to select a different color table (in the "plot style table" combo box). You may have to expand the plot settings window to see it. Several color tables are provided with the basic AutoCAD package. Pick a table, look at the preview, and repeat until you find one that gives you results you like.

Where do I get one of those?

I would suggest starting with the one you are currently using, under the field that allows you to select the plot style table select it then clcik the edit button to the right, this is where you can set the colors to black and do a save as, in fact you might want to do that to start with so you dont over write your currently used ctb file accidently.