When you sign up for a custom search engine using expertrec from https://cse.expertrec.com?platform=cse, you will get a piece of code to add to your website to take search live.
You can get your expertrec custom search code by going to this link. https://cse.expertrec.com/csedashboard/home/code
Option 1- Overlay mode (Search results on same page).
The second part <ci-search><ci-search> just adds the search box. Here is a JS fiddle link where you can understand what the code does.
You can fine tune the search box’s look and feel in your expertrec control panel from this link- https://cse.expertrec.com/csedashboard/looknfeel/inputbox
Option 2- Search results on different page.( search results open in a new page).
For example, when you want your search results to come in a different page https://www.expertrec.com/search-results, enter under search result path /search-results/
Enter your desired query parameter- q, (for wordpress usually it is s)
Now click on Apply.
Now you will get a new piece of code.
The <ci-search-results></ci-search-results> html code have to be added on your search results page for displaying the search results.