change colours, move the menu, reduce height of menu, add shadow

Dear support,

I want to edit several layout options in the free version of the kathmandu theme. I wonder if you could help me locating the files (css/php) where i can edit these:

– I want to change the colours of the main menu and the page (orange and red)
– I want to move the menu to left, under the logo/ and reduce the height of the menu and header
– I want to add a shadow on page sides (separating the main page with the background picture/colour with a line or shadow)
– by the Homepage featured content: add texts in the picture with orange/red under-colour

my page is https://benjoytours.com/wordpress/en_US/

I really hope that you can help me with this.

kind regards,