This extension is capable of making smart search component of joomla index the custom HTML modules of your site. We advise you to open the zip file and study readme.txt file before installation of the package in your site to learn about the conditions to be set in custom HTML modules so that the package will be effective on them.
Therefore the procedures:
1- Study readme.txt
2-Set already created custom html modules based on the conditions mentioned in the text file
3-Upload and install the package
4-Check if all plugins are enabled/published
5-Employ smart search and index
6-You may go to custom modules and update the indexed items or create new ones
In the pro-version of this package you need not to perform any settings manually and everything shall be done automatically which means already created custom HTML modules shall be
adapted on installation of the package so that smart search could index them.
Read more https://extensions.joomla.org/browse/new/extension/search-a-indexing/searchcustomhtml