Go to Listings -> Unlisted Products and filter to display products not listed in by the storefront that you would like to create the listing for. This will bring up a list of all the products that currently do not have an active listing on that sales channel.
Select the checkbox for the product you would like to create the listing for and click the queue listings button under the actions drop-down. This will move that product from Unlisted Products to Queued Listings.
Navigate to Listings -> Queued Listings and find the product you just queued up to be listed.
Depending how much information you have entered in for your product will determine the activation status for that listing. Your listing will either have a status of ready, edits required, or failed(ready to create listing).
Click the edits required link to pull up the listing editor. ecomdash will tell you what edits still need to be made in red in the top left corner of the listing editor before your listing is ready to send off to the sales channel.
Once you have satisfied all of the requirements to create your listing, the status will change from edits required to ready.
Click the "Create Listings" button to send any listing with a ready status to your sales channel.
You can view the status of your listing under Support -> Listing History.