At this point, as you said being an amateur, I think the easiest way for you to migrate a website from one host to another is using a plugin, which makes the migration way easier. Try something like - All In One WP Migration, or Duplicator plugin

Besides that it seems that you have not migrated the Database. Just migrating the wp-content folder does not do the job.

I assume you already have an working application in the server. You need to do the following:

1. Locate the phpMyAdmin or a db manager in you hosting website.

2. Create a new database(name, username, password and host(usually localhost). Save those values because you need to edit them later in wp-config.php file.

3. In phpMyAdmin select the db and find the import tab and upload the database.sql file you had.

4. Now you should edit the wp-config.php file of your new wordpress installation directory. This meaning updating the following lines:

   define('DB_NAME', 'your_database_name'); // Replace with the new database name

   define('DB_USER', 'your_database_user'); // Replace with the new database username

   define('DB_PASSWORD', 'your_database_password'); // Replace with the new database password

   define('DB_HOST', 'localhost'); // Replace if the database host is different

5. Sometimes the URL also need updating in database. Test, if it needs, then go to phpMyAdmin and open the wp_options tabe, look for the rows with option_name values of you siteurl and update their value to match your new site's URL.

Let me know if this works for you or you need some more information.