Hi there,
You need to go to tour Appearenace / Customizer
Select the Renew Stack On layout and design you select boxed and regulate the side with you wish ex: 72% // Select Fukllwidth and & Background Color White
On Typography you will be able to adjust your font sizes and colors.
On Header you will choose Static top / Inline Regulate the height.
On Blog mark Standard and Use Global Content Layout
Hope that helps,
If you need further help please provide your website url.
Thanks,
Joao