Go to the page where you want to 'Photoshop ' something
Right click on the content and click "inspect element" (on chrome and Mozilla, there should be an equivalent option for other browsers)
Click on 'edit as HTML' after right clicking the div class you want to edit
Make any changes you wish. You can literally modify everything that's displayed on the screen (text, images, alignment, fonts etc)
You have now created your own copy of the webpage with required changes
:)