You will find a nice tutorial on the subject at the following link: https://www.youtube.com/watch?v=xCtICBkXXnc

Menú: Accounting / Configuration / Accounting / Chart of accounts. 

I recommend you to use a test database and export some accounts to an Excel file. It will be useful as a template. Choose at least the fields: External ID, Code, Name, Group, Allow Reconciliation. 

You can fill the columns in the new Excel with the data you need and import it from the same place you exported the template. The External ID is up to you. You can use it later to update the information of that record.