How to use Secure Download?

I really need help on how to use the secure download function, I've created a bucket list as seen here https://docs.grabaperch.com/docs/members/downloads/

But I'm having a hard time on understanding how to apply this part

<a href="<perch:content id="file" type="file" label="File" order="2" bucket="secure" />">
      <perch:content type="text" id="desc" label="Title" order="1" required="true" title="true" />
</a>

I mean where should I put that ? and how can I add a file name for that ? because it just tells at the end it will output this /members/download.php?file=/members_contact_details.pdf. There are a lot of unclear things here.

Please Help,

Thanks in advance.

Arvin