In order to declare, that you have an AMP page, you should use the following link in HTML code of the web-page. Reference to your original page from AMP page using rel="canonical" to avoid a duplicate content issue:
<link rel="amphtml" href="https://www.example.com/amp/page">Mobile Accelerated Pages is a technology, developed by Google in 2015 and now it is becoming widely adopted by sites, that wish to be best ranked in Google search results. AMP provides the following benefits:
1) Your content is cached at Google servers and is therefore delivered very fast, that improves experience of visitors;
2) AMP pages get rated better in search engine results;
3) Your articles may become featured with Google's Top stories carousel and gain a high visits amount.
AMP pages have to follow a certain format.