I am unable to generate a detailed sales report with information like item name, quantity, rate, GST number, etc. How can I customize or configure the sales report to add the required columns?

To generate a detailed sales report with information like item name, quantity, rate, GST number, etc. You need to add custom column for some field and make sure you are using Standard or Enterprice model of BUSY as in basic model Custom column option is not available.To see Sale report with details ,you can follow some steps:
 Step 1: Go to Display and then click on GST reports.
 Step 2: Now click on GST Registers and then click on supply outward Register 
 Step 3: Now click on option for Party to see report and filer on period and enable Show Qty. Details option and enable other option as per your requiremen and check reports.
 Now you need to add Custom column for item name in report and you can follow these steps:
 Step 1: Open your report and then click on Custom Column option.
 Step 2: Now enter any name in format name field and press Enter key.
 Step 3: Now click on Add column option then Specify the heading of the column,Show after which Column,Data type as Text,Alighment,No. of characters,Category in Data field as Inventory voucher body then click on Field.
 Step 4: Now Select the field for Item Name and save the format and then reload report from starting with select Add custom column format name during select time period for report.