1. Click Products in the top menu.
2. Search for a product or click on a category, and find the product under the Products tab.
3. Click on the product you want to edit.
4. Make the changes needed under each tab, and click Save under each tab to save changes.
Read more about the tabs in the links:
Properties
Images
Variants
Relations
Bundle
Plan
Publish
Price
Inventory
Workflow
Permissions
History
Settings