You can edit the product settings to upload the file we should deliver to buyers of that product. In your E-junkie Dashboard go to Manage Products > Edit/Clone Products, select the product and click View/Edit Product. Make sure the Single File Download box is ticked, and you should see an Upload Product File button you can click.
If you would prefer to have us pull the file from storage on your own server, you can enter a Remote Product File URL in the product settings instead of uploading the file to us. Note this option requires a minimum product price of 0.10 or higher and a paid subscription of $20/mo or more, but we can enable this option manually for your free trial period if you want to set it up and test it out before committing to a paid subscription.
See this help page for more details: