Hi Nur,
Go to Wp Admin Dashbard > Addons > Install Revolution Slider.
Create a full width slider with about 600px height or according to your preference.
Go to Appereane > Customizer > Header > Select : Stacked.
Go to Appereance > Customizer > Custom > CSS add >
.x-logobar {
display: none;
}
On Each Page you will need to click Edit Page > Once you are in your wordpress classic back end editor, scroll down and select the slider you created as Slider Above Masthead.
Hope it helps
Joao