As DennisJaamann suggested; http://www.wowza.com/forums/content.php?3-quick-start-guide.
Basically - recorded video content needs to be uploaded to your server, FTP or SCP should do the job nicely.
If you are streaming live - then you will require a live encoder. If your On-Demand content is not encoded using the h264 codec, then you will also require an OD encoder. There are lots of options for this.
For playback - you can use any flash player you like, Wowza provide an example player with the install, there's also; OSMF Strobe Media Playback, JWPlayer (longtailvideo), Flowplayer - and lots and lots of others!
Providing some more information regarding your exact goal would be helpful, and enable us to provide a better answer.