Just overwrite the file on the current website
All the files will be of same size. just need to overwrite the new file with the current website file it will change your header design. I will provide you all the file with images optimization so that it load faster on the web. Please give feedback about the color and design. If you would like to make any changes then please let me know. On your sample.png i could see that the menu bar opacity in decrease so the bg_3.png is visible on the menu. If you would like to have such than please let me know i will submit it again.