Go to Products -> Channel Products Page
In Channel Products page, Select any Product then click on Add to Channel button
Please select Bigcommerce Channel then click on next button then page redirects to Waiting to List page
In Waiting to List page, Select Product and click on Actions -> Edit Channel Product then page redirects to edit BigCommerce page
In edit BigCommerce page, select categories for normal Products. If Product has Variation need to select Variation themes then click on Save button first after that click on List to BigCommerce button
When you click on List to BigCommerce button, page redirects to Listed Items page along with Item id
If Product is Successfully listed in BigCommerce it generates the Item Id and displays in Channel item id column