Here are steps to add a search box manually in WordPress header.
Recommended read- Search for WordPress sites.
- Go to Appearence->editor
- Add the following code to the header.php file.
1<?php get_search_form(); ?>
- This will bring in searchform.php if it is present in your theme.
- You can further customize your search box by creating your WordPress custom search from here.
- Download and Install ExpertRec’s WordPress search plugin from here which will further modify your WordPress search form.
- Copy paste your API key from your ExpertRec’s control panel.
- Your new search engine will look something similar to this.