How to create apple developer account and create certificates?
Please refer this doc. https://www.raywenderlich.com/127936/submit-an-app-part-1
Submit an app or update an app on iTunesconnect:
Go to iTunes Connect.
Login with the your Apple ID.
Go to MyApps
Click on ‘+’ icon to add new App
Check iOS platform, write Your App Name (This will be visible on AppStore), Primary Language, Choose Bundle ID (It should be added from the apple Developer) and finally add SKU (A unique ID for your app that is not visible on the App Store.)
Click on Create
Add Name, Privacy URL of your site and ratings.
Pricing And Availability
Add Pricing related information here, or keep it as free.
Add new Version and select iOS.
Add 5 screenshots of each 5.5 display (Iphone 6 plus) and 12.9 display (Ipad Pro).
Note : If you don't have required devices then refer online screenshot generator for iOS
Brief what your app all about is.It appears on the AppStore.
Support and Marketing URL
This is the support and Marketing URL for your app.
Add copyright content here.
This icon will be used on the App Store and must be in the JPG or PNG format, with a minimum resolution of at least 72 DPI, and in the RGB color space. It must not contain layers or rounded corners.
How to Remove Alpha?
-- Open your image in the Photos app from the mac, and click on export and check no alpha while exporting.
Choose option as per the app content.Based on the rating your app will be visible to desired age group.
App Review Information
Add your contact and demo account details to process your app by Apple team. Please note demo account details will not be displayed on the AppStore.
After successful adding all the information click on submit for review.
At the end give the answers of all the questions related to the cryptography and app ad, generally keep it as ‘NO’.