' creates a set of the record which matches the record you want
set dbs = currentdb
set rst = dbs.openrecordset("SELECT * FROM tblYourTable WHERE fldYourKey =" & "'" & txtYourKey & "'", dbopendynaset)
[txtCopyOfData] = rst![fldYouWantToCopy]
The txtCopyOfData should be bound to the field you want to store it in. It fairly vague i know but should get you going in the right direction as there wasn't much detail.