The following lines show how to attach the Pufferfish are Famous online article to the Novice instance of the Pufferfish DITA map:
<?xml version='1.0' encoding='utf-8'?>
<controlFile>
<resources>
<resource>
<filePath>_pufferfish.ditamap</filePath>
<instances>
<instance>
<filePath>Novice.ditaval</filePath>
<attachments>
<attachment>
<displayName>Pufferfish are Famous</displayName>
<originUrl>https://www.nationalgeographic.com/animals/fish/group/pufferfish/</originUrl>
<mimeType>text/html</mimeType>
</attachment>
</attachments>
</instance>
</instances>
</resource>
</resources>
</controlFile>