You created your own server, and now you would like to move all of your apps on Heroku to your custom server, right?
If so, the first thing to do is to move your database from Heroku to a new server.
Here are the steps that explain how to do it:
Make DB backup on Heroku
heroku pg:backups:capture --app sushi
Download your database
Upload your download dump to server via SSH
scp -P 22 latest.dump firstname.lastname@example.org:~/
Import latest dump into your newly created database
pg_restore --verbose --clean --no-acl --no-owner -h localhost -U ubuntu -d opend_production ~/latest.dump