Sitelink Search Box

[shanayabindra]

Hello Guys,
 
I have mostly heard about the sitelink search box which is visible on the google search. I have seen many e-commerce website like filpkart, amazon, cartrade & many more having this feature. So, I want to have that on my website. I have made many tries, but I failed. Can you please tell me by seeing my website, that any modification I need to make on my website . If no then please let me know there are any successful php plugin for sitelink search box via which I can install it on my website too.
While I was searching in google about this issue, I found this code that should be inserted in the website.I have put this code but found no result. Plz check

 

<script type="application/ld+json">
{
"@context": "http://schema.org",
"@type": "WebSite",
"url": "https://www.example-petstore.com/",
"potentialAction": {
"@type": "SearchAction",
"target": "https://query.example-petstore.com/search?q={search_term_string}",
"query-input": "required name=search_term_string"
}
}
</script>

 

Please help me out with this issue.

 

Thanks in advance

The page I need help with: http://autoportal.com