How to add a search box to a website

Question

I have tried a lot but can't understand it

Answer 1

to add a search box you can use <input type=text name=search>
now in js you can add other components set event listeners needed as you want to search and set a submit function for query
rest is of server side you can add PHP method that searches
this is not internal search or index search this is general search used

Answer 2

what would you search? Something from a database? we need more Information.