You can use Jamf Composer or a third-party packaging tool to build PKGs. The following workflow uses Jamf Composer. If using a third-party packaging tool, refer to the developer's documentation for instructions on repackaging. For more information about building packages using Jamf Composer, see Package Building in the Composer User Guide.
Now that you have a PKG that is signed by a valid certificate, you are ready to upload.
For instructions on uploading this file to Jamf Now, see Uploading Mac Packages to Jamf Now. Once uploaded, assign it to a blueprint to distribute the app to your team.