Action Details
Requirements and how-to articles for Twitch's action:

Create and setup your channel page on Twitch.

You need this to get it done:

Choose a username for your channel.
Must be between 4 - 25 characters long.
Once you have created your Twitch account, upload an avatar image. Your avatar is displayed next to your account throughout Twitch and serves as the preview thumbnail when linking to your Twitch channel on other sites.
Maximum file size: 3MB
Cover Image
In addition to your avatar, your cover image is one of the most prominent features on your profile.
Recommended resolution: 1200 x 480 pixels
Maximum file size: 3MB
Info Panels
Info panels are a place where you can show your personality and give viewers the information they need about your stream. Some common uses include a short description of you/your stream, your streaming schedule, social media links and chat rules. You can use Markdown for text formatting.
Info Panel Images (optional)
Maximum resolution: 320 x 300 pixels
Maximum file size: Must be under 2.9 MB
Video Player Banner
The video player banner is an image that will be displayed on your channel's video player while you are offline.
Maximum file size: 3MB
Recommended resolution: 1920 x 1080 pixels (try and keep any important information and/or content near the centre of the image)
Requirements missing or found errors? Report

How-To Articles
A list of useful links for you:

Twitch Customer Support - Channel Page Setup
Setting up your channel page is one of the most important aspects of being a broadcaster. Your channel page will be where your viewers and other users can find information about you and your broadcast.
Twitch Customer Support - Create an Account with Twitch
Creating an account on Twitch allows you to interact with broadcasters and the community via chat, follow your favourite broadcasters to receive alerts when they go live and, of course, broadcast to the Twitch community from your own channel.
Twitch Customer Support - Markdown Basics
You can use Markdown in your channel's Info Panels to help customise your page even more by adding things like headers, horizontal rules, or even lists.
Link missing here or found errors? Improve How-Tos