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

Requirements
You need this to get it done:

Header Image
The recommended size for a Twitter header image is 1500x500 pixels. On mobile, it’ll be cropped to a 2:1 aspect ratio. Use a .gif or .png file for vector-based and line art images. For photos, use a .jpg/.jpeg or .png file.
Profile Photo
The recommended image size for your profile photo is 400 x 400 pixels, but if the image you choose is a different aspect ratio, you can crop it to the square you want to use as your icon. Choose a profile photo that visually represents your business or brand and fits well in a small space. This image isn’t just on your profile page; it is visible in the top left corner of every Tweet you post.
@username
Your @username is your unique identifier on Twitter, and whilst you can change it, it is recommended to try and stick with the same one as it also determines your profile URL (e.g. a username of "@john_smith123" results in a profile URL of "twitter.com/john_smith123".) It can contain up to 15 characters (including letters, numbers and the "_" symbol) and should help people easily find your business. It is separate from your display name.
Display Name
Your display name is different from your @username in that it does not have to be unique, can contain spaces, symbols and emojis, and can be up to 50 characters long.
Bio
You have 160 characters to let people know what makes your account special, and why they should follow you. Include useful information, such as what you tend to Tweet about, your location or business hours, and a link to your website. Use a unique link, so you can track visitors to your site from Twitter.
Pinned Tweet
Keep an important Tweet at the top of your timeline by pinning it there. Click on the “more” option on the Tweet you want to pin and select “Pin to your profile page.”
Phone Number
If you decide to sign up using a phone number, you can choose to receive your account verification code via either SMS or a voice call.
Email Address
If you decide to sign up using an email address, you will get your account verification code emailed to you.
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How-To Articles
A list of useful links for you:

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Twitter Help Center - Signing up with Twitter
How to create a Twitter account.
Official
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