In order to push or pull content from LinkedIn, a user must be authenticated and grant permission to do so. You'll need to get authentication working properly with LinkedIn before you'll be able to setup a channel. Let's get the issues resolved from
your other post
and we'll gladly help with getting a channel setup.
In general though, setting up a channel is straight forward. The most difficult part is applying to use LinkedIn's Marketing Program, which is a requirement for API access to fetch a feed or push new content to one. The application is straightforward, but approval is out of our hands.
Thanks,
Alex