change text in search bar

Hi

I am web admin for desitripper.in
I need help in customizing the theme
in the tours page, I want to customize the text in this page: https://www.desitripper.in/tours/
search bar area
for example: search tour > change to search trip
tour type to trip type etc

so I need to know where to change it
or which file to edit
I am experienced in php and css but I need to know which files to edit
thanks