Hi, I think you can refer to the standard report.
for example, Standard Sales - Order Conf. (1305)

Source Code and layout file:
[View:/cfs-file/__key/communityserver-discussions-components-files/758/StandardSalesOrderConf.Report.al]
[View:/cfs-file/__key/communityserver-discussions-components-files/758/StandardSalesOrderConf.docx]
[View:/cfs-file/__key/communityserver-discussions-components-files/758/StandardSalesOrderConf.rdlc]
Hope this helps.
Thanks.
ZHU