i'm trying to set up a custom search ad, but I am nost sure about the query.

On the site it says

(https://developers.google.com/custom-search-ads/docs/implementation-guide)

'query' should be dynamic based on your page. This variable targets the ads and therefore should always match what the user on your site has just performed a search for.

Now, what I understand is: I have to program my page so that the query variable contains some custom words.

Am I right?

If a user gets to my site through clicking on an adsense, there is no way to "know" what the user looked for and display my query accordingly, right?

Thanks for any help!