Hi @bassemsaad,
I installed the plugin Loco Translation. This is the free plugin and you can translate your text here.
Go to Loco > Themes > Biolife and change: https://prnt.sc/u0p58m
About customizing the header, how do you want to do? Change color, menu, ... Please take the screenshots and let me know clearly. Then I will check for you
Regards,
Yame