Customer group for customers summary

I am new to manager
So I wanted to know how to create customer summary for particular group of customer?

You cannot create customer groups. Where are you trying to group them and for what purpose?

I am trying to group them in customer summary section in report tab.
I wanted to know transaction summary of customers belonging to particular sales agent

Is there a way to export customer summary with customer code i have assigned to each customer

Then i create group in spreadsheet

You can create customer groups by using custom fields - Once you have created custom fields for each customer you can search that field from the customers tab and export the details to a spreadsheet.

You could also create reports by using that custom field. For example, there is the Sales Invoice Totals by Custom Field report. You could also build a custom report.

Thank you