Magento uses EAV database structure, so it's very hard to transfer the data manually. You need a script or a tool/extension to do that.
Currently there're 2 ways toTo migrate from Magento 1 to Magento 2:
Install this data migration tool extension to your Magento 2 store, then perform the migration: https://github.com/ubertheme/magento2_data_migration/releaseshttps://devdocs.magento.com/guides/v2.2/migration/bk-migration-guide.html
Hire a Magento 1 to Magento 2 migration service or Magento experts, they will take care of the migration for you.
Don't forget to create a backup before performing the migration.