There is not enough memory to process your import. Try to split your import into smaller chunks.

FYI. In upcoming v1.2.11 import process will be improved with task processing and you do not need to break import CSV file into parts.

Do you get any errors in the log after you ran import? Check settings for the images in System -> Settings -> Appearance or in the template edit section.

Unfortunately, there is not easy way if you non-technical.
You will need to do SQL insert into your database.

You can locate original database with all countries in here:
https://github.com/abantecart/abantecart-src/blob/master/public_html/install/abantecart_database.sql

Look for:
INSERT INTO `ac_countries`
and
INSERT INTO `ac_country_descriptions`

Do not forget to clear Abantecart cache after direct inserts or updates into database.

White screen is indication of your web server or PHP failure.

You need to check 2 log files to identify the error

1. Locate your web server error log and check the end of the file for the error.
Post it here.
Post of the time, it will be missing package on your server or incorrect permission of some file

2. Locate your AbanteCart error log in ../system/logs/error.txt
See what is there at the end of the file.

If there is nothing in those logs, check permissions of main index.php file. It must be 755 or 644 (777 will not work)

Did you double check that all files are uploaded? Try to re-upload and check that there is no error after upload

First, make sure you configure your domain or access your site with domain that is configured in store settings.

Probably www.greatatlantictrophy.com and not ftp.greatatlantictrophy.com or mail.greatatlantictrophy.com as it say in the log

I am ready to help