Go to Setup and search with the outbound keyword:
An Outbound Change Set contains customization that you want to send from this organization to another organization. This customization could include new components or modifications to existing components, such as apps, objects, reports, or Apex classes and triggers. An Outbound Change Set can't be used to delete or rename components in another organization.
To create a new Outbound Change Set, hit the New button.
Add the name of the Change Set, which is mandatory, and enter its description:
Hit the ...