How to Group the names in crystal reports?

Create two Group like Seller and Buyer

1) Right Click Group name fields in field explorer , 

2) click Insert Group, Under Common Tap , Select your Seller Name in that Combo Box,

3) then click ok, now your report will show Groups.

4) do the same for Buyer. Create Second Group.

5) and place your DataSource Columns inside of respective Groups

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If any problem with this, please show your table Structure . it will help us to help you
Thank You