Heroku file system is ephemeral - that means that any changes to the file system whilst the dyno is running only last until that dyno is shut down or restarted. Each dyno boots with a clean copy of the file system from the most recent deploy. This is similar to how many container based systems, such as Docker, operate. In addition, under normal operations dynos will restart every day in a process known as Cycling So due to that problem they suggest me to use S3 bucket but I was still student I didn't have credit card for verifying my account on (Amazon Web Services) AWS. In my way of figuring out what can I do I found cloud storage called Cloudinary this cloud storage provides an API for uploading images, videos, and any other kind of file to the cloud. and it allow secure uploading from your servers, directly from your visitors' browsers or mobile applications, or fetched via remote public URLs.
So without being said let give out the steps but before getting started let's assume that you have Django website which uploads images to the server and render it out dynamically.