Double entry basically just means that for every transaction on your books, you are showing where the money/asset/liability came from and/or where it's going. If you enter that you paid $100 for the AWS bill, you need to indicate from what account that money came from. So you would debit AWS Expense and you would credit your Wells Fargo Checking Account. With modern software, this basically just amounts to entering the expense and specifying which account it came from.