I have recently gone through something similar, and so have done a lot of research on what is out there.
There are a few things you will need:
- A camera
- A software or hardware encoder
- A software or hardware capture device
- A decent internet connection (upload rate must be greater than your stream rate)
- An online service, or your own server
There are also some major considerations, such as the internet connection speed of your audience, the types of devices the target audience will be watching on, and of course, your budget.
Assuming the worst case scenario, no budget at all, you are limited to free services such as Livestream, Justin.tv, YouTube, and Vimeo. There are some cons to each service, but for free they really are very good. Some of thee cons are streaming at non-HD resolution; the displaying of advertisements before, during, or after your broadcast; no video analytics; and/or, no video archiving after the live event has finished. So you will have to research what best suits your needs.
Livestream.com does not have ads, does not have archiving, but it does have easy-to-use software and service. So it would be my choice to stream for free. You can only stream SD quality with a free account, but here is a very simple solution that will get you streaming in no time:
- Sign up for Livestream.com's free service
- Install their Procaster software
- Install a free capture software such as Open Broadcast
- Test your webcam with OBS, then connect it through to Livestream using this tutorial
After you have completed the live event, you have 30 days before the event is deleted on Livestream's free account, so I would suggest downloading it for archival purposes as soon as you're done.
If you want to throw some money at it, ustream.tv, livestream.com, and justin.tv all offer entry-level plans that include archive space and better options.