You will find the styles for these sections in your style.css style sheet in your WordPress Theme folder.

How you change these sections in preparation for printing is up to you. You can still print the sidebar but not the footer, or include the footer but not the sidebar, change font styles and sizes, or even tell it to print images or not. We will give you some examples and the rest you can figure out on your own by experimenting.
Creating Print Styles

Styles associated with printing can be set in two different ways. If you want very simple changes to the site for easy printing, you can use the first method and add them directly to the style sheet. If you want to control the end result of your site when printed, it is best to keep these in their own print.css style sheet.

Note: Some WordPress Theme authors may have already thought ahead and included print styles for their Theme. Check the Theme folder for a print.css style sheet file and in the style.css for references to print before proceeding.