Create Package

To setup a new package, so the following steps:

1. Create a extension manifest file
2. Upload the zipped extension
3. Create a new package
4. Create the first version

Create a extension manifest file

To serve a Joomla! version info request, you have to provide a manifest-XML file, wich will be sendet on request. A Joomla! installtion elsewhere will ask your server for update informations for your extension. To publish your extension in this way, your extension manifest file must have an entry, specifying the address to look for a new version.
See Joomla! documantation - Deploying an Update Server

<extension>
  <...>
  <updateservers>
    <server type="extension" priority="1" name="My Extension's Updates">http://example.com/extension.xml</server>
  </updateservers>
</extension>

In the next step, you have to creae a manifest file at the manifests folder at the admin section of the package manager. This file will be used to serve the version request. Some of the xml-tags like the version and the downloadurl will be replaced by the package manger.

<updates>
  <update>
    <name>Your extension</name>
    <description>Joomla! 3.9 CMS</description>
    <element>com_yourextension</element>
    <type>component</type>
    <version>1.0.0</version>
    <infourl title="Logical-Arts Subscriptions 1.0.0">http://example.com/info-25-5-0.html</infourl>
    <downloads>
        <downloadurl type="full" format="zip">http://example.com/downloads/com_yourextension</downloadurl>
    </downloads>
    <tags>
        <tag>stable</tag>
    </tags>
    <client>site</client>
    <maintainer>You</maintainer>
    <maintainerurl>Your site</maintainerurl>
    <section>Updates</section>
    <targetplatform name="joomla" version="3.[89]" />
    <php_minimum>7.2</php_minimum>
    <folder/>
  </update>
</updates>

Upload the zipped extension

Upload your extension to the downloads directory of the package manager.

Please note, you can specify an specific file for a downloadable version or, set the filename to auto with prefix, wich will generate the filename dependend of the version being set. This will result in a filename like: "<prefix>_<version>.zip"

Create a new package

• At the admin area, select Components -> Logical-Arts Package Manager.
• Select Packages from the sidebar menu.
• Select New from the button bar

Create the first version

• At the admin area, select Components -> Logical-Arts Package Manager.
• Select Versons from the sidebar menu.
• Select New from the button bar