Making The barcode from CSV file
Save the numbers into a CSV file.
To include an Add-on in ISBN / ISSN in your CSV file separate your Code number with a | (Bar) e.g. 123456789|01 for ISSN

Next open up the Barcode X software. It should look like the image above.
Select the code type you will be using from the top menu.
To set the location of the folder your barcodes will be saved into, click the top menu again,
then choose Options, then Save To Specific Folder.

Click to the Page Tab (3rd one along on the top of the 2 tab rows).

The window should look like the one above.
Click in the File Name box and locate your CSV file and click Open.

The Item(s) field is the data for the barcode, in this case <<1>> means the first column of the CSV file.
The Start At Line field is set to 1 in order to start the sequence at the first line of the CSV file.
You would use 2 if you wanted to omit headers from the file.
Setting the Item For Name field to 0 will cause the file to be saved with the barcode number as its file name.
The Get How Many tab is the number of items (barcodes) to be made.