Setting up Firefox so that you can take a screenshot of a website and then draw on it with simple boxes, lines and text is quite easy. This functionality can be added using the Firefox extensions / addons. Similarly you can add a screenshot extension to Google Chrome for the same purpose.
1. In Firefox open the Tools > Addons
2. Click into the addons search box and type “screenshot”
3. Next to the Awesome Screenshot addon click the install button
4. Open a new tab in firefox and you will see the camera lense icon for the screenshot plugin, click it.
5. Typically you will want to select the ‘visible part of the page’ to screenshot