This video tutorial describes how you can easily create a Twitter App: https://youtu.be/Bhc7q8p2RYY
Step 1. Firstly sign in to your Twitter account.
Step 2. Follow this link https://apps.twitter.com and create a new Twitter app by clicking the “Create New App” button:
Step 3. Upon creating your app, you’ll be transferred to your application creation page. Enter your application’s name, its description (for example, App for auto-posting) and your Website URL in the fields. Read and accept the “Twitter Developer Agreement” and check the box next to “Yes, I agree”. Push the button “Create your Twitter Application”:
Step 5. Go to “Keys and Access Tokens”. You will see API Key and API Secret. Your Twitter application is ready to use.