I can't get this. I'm so confused how to journalize in the periodic method.

THe following transactions occurred during April of the current year:
April 03 purchased $12,000 of merchandise (2/10, N/30)
April 07 Merchandise of April 03 Returned, $800
April 10 Sold goods costing $4000 for $7600
April 12 Paid for April 03 purchase
April 23 Sold goods costing $1050 for $1800

1) redord the journal Entry of the above using periodic method.

We don't just do people's work for them, and your transactions are involved quite a bit of a merchandising chapter. So I will give you a link you may want to read over and see if you can get a better idea of how this all works and make an attempt from there to do these. You can post your attempts if you like and someone can check them.
http://www.principlesofaccounting.com/chapter%205.htm