Add 3 columns below slider

I totally took on a project too big for me. Years ago I taught myself html and css and now have completely forgotten it.

I want to create three columns under the slider. See this example: http://impact100pensacola.org/

I completely forgot the basic code for that. I’m pretty sure I would first need to create CSS to define styles and then some divs.

If someone could create a code, and I could modify the styles, that’d be great!

Thanks!