Data Scraping Dynamically (Selector)

Hello there,
i want to make a robot that takes a user input searches for it on google scholar and writes the title of evry source in an excel worksheet. I was bale to do anything but not to individually search for the users input. When i try to change the selector it is invalid,
please help me with that issue!
I know this questions was already answered but i wasnt able to take the advice from there.