I finally found another post that is directly related, and I thank you PhilModJunk. http://forums.filemaker.com/posts/a57a47704b
Since I am practically a total newbie, I still had a problem with writing the calculation for Set Field, basically, had to pick the field from "specify" then ok, then click on calculation to write the calculation. Also it helped to show all script steps by name instead of category. Anywhere here is the final result which I am quite satisfied with for now.
Enter Find Mode 
Set Field [CustomerTable::CreatedBy ; Get ( AccountName ) ]
New Record/RequestSet Field [CustomerTable::CurrentSalesRep ; Get ( AccountName ) ]
Set Error Capture [on]
Perform Find