download open broadcaster software from here: http://obsproject.com/
its an easy to use and low resource using streaming program thats free to use.
get your streamkey from twitch on this link: http://twitch.tv/broadcast/dashboard/streamkey
copy it into "settings -> broadcast settings" and set the server nearest to your location (dont use the frankfort server tho)
add hotkeys for starting / stopping the streams in the same settings tab.
get on the encoding tab and set the wanted bitrate, while using CBR (constant bitrate), ive got around 6000kb/s upload, using 2500-3000kb/s bitrate.
audio on aac codec, 128 bitrate, format 48 khz stereo
Video tab: select the right video card, set your base resolution to custom and use 1920x1080, use resolution downscale on 1.50 (1280x720) Filter: Lanczos, FPS: 30
Audio tab is kinda default, just make sure you are using the right mic & audio device sources.
if you are using push to talk on teamspeak, put the same key here as well.
Advanced tab: enable multithreaded optimizations, process priority on normal
i suggest using veryfast or faster as the x264 cpu preset, as everything else is stealing waaaays too much cpu power = low fps ingame
im using the x264 encoding profile "main", no idea what it does.
everything is is unchecked for me, just make sure to put "Keyframe Intervall" to 2 as otherwise twitch suggests you to put it to 2 ^^
on twitch you basically just need the twitch.tv/yourusername/dashboard where you can edit everything you need for your stream on twitch.