OK, I know how to get to this file,
I am use this guid : Crossmark
I am now in Steps 3 & 4 :
Step 3: Add Crossref DOI to HTML pages and PDF
<meta name=”dc.identifier” content =”10.3333/1212212”>
Step 4: Apply crossmark button
<!-- Start Crossmark Snippet v2.0 -->
<script src="https://crossmark-cdn.crossref.org/widget/v2.0/widget.js"></script>
<a data-target="crossmark"><img src="https://crossmark-cdn.crossref.org/widget/v2.0/logos/CROSSMARK_BW_horizontal.svg" width="150" /></a>
<!-- End Crossmark Snippet -->
But where do I put the html code, and meta, and where do I put the javascript code.
where is the appropriate place?.