Agile retrospectives are a chance for a development team to discuss and reflect on how to become more effective.
They are a great chance to fine-tune how you work; to celebrate the wins, to discuss the failures, and to highlight questions and tasks for the interation / sprint ahead.
By doing this, you can figure out what works well for you and your team, and make small adjustments towards having a happier and more productive development team.
As a team, you discuss how the last iteration / sprint went. In our case, we have a meeting every Friday.
You talk about anything that went well and anything that went poorly. You make a note of questions raised that need answering and things to do before the next retrospective.
Get your team together, and use whatever voice tools you'd normally use to get everyone to call in; this replaces the whiteboard / cardwall you might normally use.
Skype, Hangouts, or a phone; whatever suits you.
Invite your team members to it by sharing the URL.
When they open it in their browser, on their laptops, or their mobile devices, or even their Kindles (yep!), they are connected in real time and everyone sees updates automagically.
Add items to the four groups:
Good things that happened, bad things that happened, tasks for the upcoming sprint, and questions raised during the meeting.