Step 1:First of all, Goto the Chrome Web Store, Download and Install Facebook Themes Extension.Step 2: Install the Facebook Theme Extension by clicking on Free or Add to Chrome Button on Top Right hand Side of the Web page. (Feel free to Check the Reviews about this extension before installing.)
Step 3: It will take just a second to download the Extension, Now Click on Customize and Control Google Chrome Button > Tools > Extensions OR Alternatively you can just Type : chrome://extensions/ in your address bar to show up all installed extensions
Step 4: Now if you have Many Extensions Installed, Look for Facebook Themes Extension and Click on“Option” .
Step 5: After Click on “Options” Click on “Explore” Tab to Show up all the available facebook Themes to Choose from.
Step 6: Choose any theme of you choice by Clicking on “Install” , The facebook theme is now installed, Click on Installed tab to verify.
Step 7: By now, every thing is Done. Open Facebook and Check the New theme, You may change it later on by Choosing another theme from the list of Facebook themes provided there.