The aim of the retrospective is to discuss and plan possible improvements of quality and effectiveness.
The focus of the retrospective is on the team creating the product and this event is for the team to inspect their performance.
The last iteration is inspected with regards to individuals, interactions, processes, tools, and their Definition of Done.
The most important findings should be addressed as soon as possible to get the advantages coming from the improvement right away.
During the retrospective, the three questions are usually discussed: what went well, what problems were encountered, and how those problems were or can be solved.
Do not assign blame, instead try to get to the origins and the roots of the problems, that were discovered.