Promoting a Flow
One a Lifecycle has been created, including it's stages, a flow can be promoted to the different stages following the progression of this flow.
The promotion stages can be found at the top of the flow building window.

Important
A flow can only be promoted from one stage to the next once it has completed its process in that specific stage and is ready to go tot he next stage.
Add a flow or navigate to the flow you wish to promote.
When a flow is created or imported, it is automatically in the Development stage. it is during this stage that the flow is built and can be edited. Once it has completely been developed and is ready to pass on to Test, click on the three dots in the upper right corner and select Promote.
If required, apply changes to the SFTP connections and click Promote Flow.
A message will appear for a short period of time letting you know that the flow has been promoted successfully from dev to test, and the flow will be in Test status.
When the flow is in Test, it will undergo a testing period to validate if the flow has been built and configured correctly. In Test, the flow cannot be edited. Once the testing period is over, the flow can be promoted to Production. Click the three dots in the upper right corner and select Promote.
If required, apply changes to the SFTP connections and click Promote Flow.
The flow will be in the Production stage.