In Sun Systems
You need to produce and then save a CSV(comma delimited) file that contains 2 columns; GL Code & Description
Go to the Admin tab> GL Codes; Edit
Click on the green 'Browse' button as shown circled in red in image below
Select your previously saved CSV file and then click 'Upload'.
It will ask you 'Does the uploaded file contain a Header row?' If your CSV file has a heading at the top of the columns, then click Yes. If it doesn't then click No.
The file will now upload and when finished you will receive a message saying 'GL Codes were imported successfully' and it will tell you how many etc.