You have come to the right place today for this easy fix!
Online Store > Themes > Theme name > Edit Code > Layout > theme.liquid
In your theme liquid file, do a quick search for /search to find the search form.
Look for this line:
This line tells your search to only show results for products. We want it to also include pages and blog. We need to add the values page and article. Use comma but do not use space.
Your new line of code should look like this:
Your Shopify store search will now search products, pages, and blog posts.